How to add syntax highlighting to <marked-element>? - polymer

I've been trying to add syntax highlighting to <marked-element> using <prism-highlighter>, but I am at a complete loss on how to get this to work.
When reading the documentation for <prism-highlighter>, it states "This flow is supported by <marked-element>", but isn't clear on how to use them together.
When looking into the <prism-highlighter> source on the GitHub, the only demo given is for when using it alone, and using it this way would miss all the benefit of <marked-element>.
I could access the content with <marked-element>.markdown, but I can't figure out how I would process it and send it back, and every attempt to do so failed.
How do I used <marked-element> for the markdown, and also add syntax highlighting?
Or maybe change the iron-demo-helpers' <demo-snippet> so that I get the nice layout with the copy button, but for different languages like bash and python scripts. (Which are both supported according to the supported languages on the PrismJS website.)
Edit: It turns out that it wasn't how I was doing it that was wrong, but that the language I was using wasn't supported by default. Posted solution as answer below.

Insert the <marked-element> with your code after the <prism-highlighter> tag, just as below:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<link rel="import" href="/bower_components/marked-element/marked-element.html">
<link rel="import" href="/bower_components/prism-element/prism-highlighter.html">
</head>
<body>
<prism-highlighter></prism-highlighter>
<marked-element>
<script type="text/markdown">
```html
<div>yes</div>
<i>
console.log( "no log" )
</i>
```
</script>
</marked-element>
</body>
</html>
The highlighter will detect and style the elements inside the <marked-element>.

So the reason it wasn't working is because I didn't realize it was coded in the element to only support a few languages.
My solution was to edit/fork the prism + prism-element components.
(Note: If you edit the files inside bower_components without changing the name or directory you may lose changes upon next update)
I edited the prism-element/prism-highlighter.html file to include additional languages:
if (lang === 'js' || lang.substr(0, 2) === 'es') {
return Prism.languages.javascript;
} else if (lang === 'css') {
return Prism.languages.css;
} else if (lang === 'c') {
return Prism.languages.clike;
} else if (lang === 'bash') { // Check for bash markdown
return Prism.languages.bash;
} else if (lang === 'python') { // Check for python markdown
return Prism.languages.python;
} else {
...
The prism/gulpfile.js to import more language components:
paths = {
componentsFile: 'components.js',
components: ['components/**/*.js', '!components/**/*.min.js'],
main: [
'components/prism-core.js',
'components/prism-markup.js',
'components/prism-css.js',
'components/prism-clike.js',
'components/prism-javascript.js',
'components/prism-bash.js', // Include bash component
'components/prism-python.js', // Include python component
'plugins/file-highlight/prism-file-highlight.js'
],
...
If you changed the name/path of prism, make sure to change the relative paths in prism-element/prism-import.html.
Then in the prism folder run npm install to install dependencies, and gulp to run gulpfile.js and compile to prism/prism.js.
Since I named my fork prism-highlighter-plus, my final code looks like this:
<link rel="import" href="../../bower_components/marked-element/marked-element.html">
<link rel="import" href="../../bower_components/prism-element-plus/prism-highlighter-plus.html">
<dom-module id="backup-script">
<template>
<style>
:host {
display: block;
}
.markdown-html {
overflow-x: auto;
}
</style>
<prism-highlighter-plus></prism-highlighter-plus>
<marked-element>
<div class="markdown-html"></div>
<script type="text/markdown">
```bash
#!/bin/bash
...
excluded_databases="Database|information_schema|performance_schema|mysql"
databases=`mysql -u $mysql_user -p$mysql_password -Bse "SHOW DATABASES;" | egrep -v $excluded_databases`
for db in $databases; do
mysqldump -u $mysql_user -p$mysql_password --databases $db > $mysql_output/$today/$db.sql
done
...
</script>
</marked-element>
</template>
<script>
Polymer({
is: 'backup-script'
});
</script>
</dom-module>

Related

Is there a way to link html sections to an html file? [duplicate]

I have 2 HTML files, suppose a.html and b.html. In a.html I want to include b.html.
In JSF I can do it like that:
<ui:include src="b.xhtml" />
It means that inside a.xhtml file, I can include b.xhtml.
How can we do it in *.html file?
In my opinion the best solution uses jQuery:
a.html:
<html>
<head>
<script src="jquery.js"></script>
<script>
$(function(){
$("#includedContent").load("b.html");
});
</script>
</head>
<body>
<div id="includedContent"></div>
</body>
</html>
b.html:
<p>This is my include file</p>
This method is a simple and clean solution to my problem.
The jQuery .load() documentation is here.
Expanding lolo's answer, here is a little more automation if you have to include a lot of files. Use this JS code:
$(function () {
var includes = $('[data-include]')
$.each(includes, function () {
var file = 'views/' + $(this).data('include') + '.html'
$(this).load(file)
})
})
And then to include something in the html:
<div data-include="header"></div>
<div data-include="footer"></div>
Which would include the file views/header.html and views/footer.html.
My solution is similar to the one of lolo above. However, I insert the HTML code via JavaScript's document.write instead of using jQuery:
a.html:
<html>
<body>
<h1>Put your HTML content before insertion of b.js.</h1>
...
<script src="b.js"></script>
...
<p>And whatever content you want afterwards.</p>
</body>
</html>
b.js:
document.write('\
\
<h1>Add your HTML code here</h1>\
\
<p>Notice however, that you have to escape LF's with a '\', just like\
demonstrated in this code listing.\
</p>\
\
');
The reason for me against using jQuery is that jQuery.js is ~90kb in size, and I want to keep the amount of data to load as small as possible.
In order to get the properly escaped JavaScript file without much work, you can use the following sed command:
sed 's/\\/\\\\/g;s/^.*$/&\\/g;s/'\''/\\'\''/g' b.html > escapedB.html
Or just use the following handy bash script published as a Gist on Github, that automates all necessary work, converting b.html to b.js:
https://gist.github.com/Tafkadasoh/334881e18cbb7fc2a5c033bfa03f6ee6
Credits to Greg Minshall for the improved sed command that also escapes back slashes and single quotes, which my original sed command did not consider.
Alternatively for browsers that support template literals the following also works:
b.js:
document.write(`
<h1>Add your HTML code here</h1>
<p>Notice, you do not have to escape LF's with a '\',
like demonstrated in the above code listing.
</p>
`);
Checkout HTML5 imports via Html5rocks tutorial
and at polymer-project
For example:
<head>
<link rel="import" href="/path/to/imports/stuff.html">
</head>
Shameless plug of a library that I wrote the solve this.
https://github.com/LexmarkWeb/csi.js
<div data-include="/path/to/include.html"></div>
The above will take the contents of /path/to/include.html and replace the div with it.
No need for scripts. No need to do any fancy stuff server-side (tho that would probably be a better option)
<iframe src="/path/to/file.html" seamless></iframe>
Since old browsers don't support seamless, you should add some css to fix it:
iframe[seamless] {
border: none;
}
Keep in mind that for browsers that don't support seamless, if you click a link in the iframe it will make the frame go to that url, not the whole window. A way to get around that is to have all links have target="_parent", tho the browser support is "good enough".
A simple server side include directive to include another file found in the same folder looks like this:
<!--#include virtual="a.html" -->
Also you can try:
<!--#include file="a.html" -->
A very old solution I did met my needs back then, but here's how to do it standards-compliant code:
<!--[if IE]>
<object classid="clsid:25336920-03F9-11CF-8FD0-00AA00686F13" data="some.html">
<p>backup content</p>
</object>
<![endif]-->
<!--[if !IE]> <-->
<object type="text/html" data="some.html">
<p>backup content</p>
</object>
<!--> <![endif]-->
Following works if html content from some file needs to be included:
For instance, the following line will include the contents of piece_to_include.html at the location where the OBJECT definition occurs.
...text before...
<OBJECT data="file_to_include.html">
Warning: file_to_include.html could not be included.
</OBJECT>
...text after...
Reference: http://www.w3.org/TR/WD-html40-970708/struct/includes.html#h-7.7.4
Here is my inline solution:
(() => {
const includes = document.getElementsByTagName('include');
[].forEach.call(includes, i => {
let filePath = i.getAttribute('src');
fetch(filePath).then(file => {
file.text().then(content => {
i.insertAdjacentHTML('afterend', content);
i.remove();
});
});
});
})();
<p>FOO</p>
<include src="a.html">Loading...</include>
<p>BAR</p>
<include src="b.html">Loading...</include>
<p>TEE</p>
In w3.js include works like this:
<body>
<div w3-include-HTML="h1.html"></div>
<div w3-include-HTML="content.html"></div>
<script>w3.includeHTML();</script>
</body>
For proper description look into this: https://www.w3schools.com/howto/howto_html_include.asp
As an alternative, if you have access to the .htaccess file on your server, you can add a simple directive that will allow php to be interpreted on files ending in .html extension.
RemoveHandler .html
AddType application/x-httpd-php .php .html
Now you can use a simple php script to include other files such as:
<?php include('b.html'); ?>
This is what helped me. For adding a block of html code from b.html to a.html, this should go into the head tag of a.html:
<script src="https://code.jquery.com/jquery-1.10.2.js"></script>
Then in the body tag, a container is made with an unique id and a javascript block to load the b.html into the container, as follows:
<div id="b-placeholder">
</div>
<script>
$(function(){
$("#b-placeholder").load("b.html");
});
</script>
I know this is a very old post, so some methods were not available back then.
But here is my very simple take on it (based on Lolo's answer).
It relies on the HTML5 data-* attributes and therefore is very generic in that is uses jQuery's for-each function to get every .class matching "load-html" and uses its respective 'data-source' attribute to load the content:
<div class="container-fluid">
<div class="load-html" id="NavigationMenu" data-source="header.html"></div>
<div class="load-html" id="MainBody" data-source="body.html"></div>
<div class="load-html" id="Footer" data-source="footer.html"></div>
</div>
<script src="js/jquery.min.js"></script>
<script>
$(function () {
$(".load-html").each(function () {
$(this).load(this.dataset.source);
});
});
</script>
Most of the solutions works but they have issue with jquery:
The issue is following code $(document).ready(function () { alert($("#includedContent").text()); } alerts nothing instead of alerting included content.
I write the below code, in my solution you can access to included content in $(document).ready function:
(The key is loading included content synchronously).
index.htm:
<html>
<head>
<script src="jquery.js"></script>
<script>
(function ($) {
$.include = function (url) {
$.ajax({
url: url,
async: false,
success: function (result) {
document.write(result);
}
});
};
}(jQuery));
</script>
<script>
$(document).ready(function () {
alert($("#test").text());
});
</script>
</head>
<body>
<script>$.include("include.inc");</script>
</body>
</html>
include.inc:
<div id="test">
There is no issue between this solution and jquery.
</div>
jquery include plugin on github
You can use a polyfill of HTML Imports (https://www.html5rocks.com/en/tutorials/webcomponents/imports/), or that simplified solution
https://github.com/dsheiko/html-import
For example, on the page you import HTML block like that:
<link rel="html-import" href="./some-path/block.html" >
The block may have imports of its own:
<link rel="html-import" href="./some-other-path/other-block.html" >
The importer replaces the directive with the loaded HTML pretty much like SSI
These directives will be served automatically as soon as you load this small JavaScript:
<script async src="./src/html-import.js"></script>
It will process the imports when DOM is ready automatically. Besides, it exposes an API that you can use to run manually, to get logs and so on. Enjoy :)
Here's my approach using Fetch API and async function
<div class="js-component" data-name="header" data-ext="html"></div>
<div class="js-component" data-name="footer" data-ext="html"></div>
<script>
const components = document.querySelectorAll('.js-component')
const loadComponent = async c => {
const { name, ext } = c.dataset
const response = await fetch(`${name}.${ext}`)
const html = await response.text()
c.innerHTML = html
}
[...components].forEach(loadComponent)
</script>
To insert contents of the named file:
<!--#include virtual="filename.htm"-->
Another approach using Fetch API with Promise
<html>
<body>
<div class="root" data-content="partial.html">
<script>
const root = document.querySelector('.root')
const link = root.dataset.content;
fetch(link)
.then(function (response) {
return response.text();
})
.then(function (html) {
root.innerHTML = html;
});
</script>
</body>
</html>
Did you try a iFrame injection?
It injects the iFrame in the document and deletes itself (it is supposed to be then in the HTML DOM)
<iframe src="header.html" onload="this.before((this.contentDocument.body||this.contentDocument).children[0]);this.remove()"></iframe>
Regards
The Athari´s answer (the first!) was too much conclusive! Very Good!
But if you would like to pass the name of the page to be included as URL parameter, this post has a very nice solution to be used combined with:
http://www.jquerybyexample.net/2012/06/get-url-parameters-using-jquery.html
So it becomes something like this:
Your URL:
www.yoursite.com/a.html?p=b.html
The a.html code now becomes:
<html>
<head>
<script src="jquery.js"></script>
<script>
function GetURLParameter(sParam)
{
var sPageURL = window.location.search.substring(1);
var sURLVariables = sPageURL.split('&');
for (var i = 0; i < sURLVariables.length; i++)
{
var sParameterName = sURLVariables[i].split('=');
if (sParameterName[0] == sParam)
{
return sParameterName[1];
}
}
}​
$(function(){
var pinc = GetURLParameter('p');
$("#includedContent").load(pinc);
});
</script>
</head>
<body>
<div id="includedContent"></div>
</body>
</html>
It worked very well for me!
I hope have helped :)
html5rocks.com has a very good tutorial on this stuff, and this might be a little late, but I myself didn't know this existed. w3schools also has a way to do this using their new library called w3.js. The thing is, this requires the use of a web server and and HTTPRequest object. You can't actually load these locally and test them on your machine. What you can do though, is use polyfills provided on the html5rocks link at the top, or follow their tutorial. With a little JS magic, you can do something like this:
var link = document.createElement('link');
if('import' in link){
//Run import code
link.setAttribute('rel','import');
link.setAttribute('href',importPath);
document.getElementsByTagName('head')[0].appendChild(link);
//Create a phantom element to append the import document text to
link = document.querySelector('link[rel="import"]');
var docText = document.createElement('div');
docText.innerHTML = link.import;
element.appendChild(docText.cloneNode(true));
} else {
//Imports aren't supported, so call polyfill
importPolyfill(importPath);
}
This will make the link (Can change to be the wanted link element if already set), set the import (unless you already have it), and then append it. It will then from there take that and parse the file in HTML, and then append it to the desired element under a div. This can all be changed to fit your needs from the appending element to the link you are using. I hope this helped, it may irrelevant now if newer, faster ways have come out without using libraries and frameworks such as jQuery or W3.js.
UPDATE: This will throw an error saying that the local import has been blocked by CORS policy. Might need access to the deep web to be able to use this because of the properties of the deep web. (Meaning no practical use)
Use includeHTML (smallest js-lib: ~150 lines)
Loading HTML parts via HTML tag (pure js)
Supported load: async/sync, any deep recursive includes
Supported protocols: http://, https://, file:///
Supported browsers: IE 9+, FF, Chrome (and may be other)
USAGE:
1.Insert includeHTML into head section (or before body close tag) in HTML file:
<script src="js/includeHTML.js"></script>
2.Anywhere use includeHTML as HTML tag:
<div data-src="header.html"></div>
There is no direct HTML solution for the task for now. Even HTML Imports (which is permanently in draft) will not do the thing, because Import != Include and some JS magic will be required anyway.
I recently wrote a VanillaJS script that is just for inclusion HTML into HTML, without any complications.
Just place in your a.html
<link data-wi-src="b.html" />
<!-- ... and somewhere below is ref to the script ... -->
<script src="wm-html-include.js"> </script>
It is open-source and may give an idea (I hope)
You can do that with JavaScript's library jQuery like this:
HTML:
<div class="banner" title="banner.html"></div>
JS:
$(".banner").each(function(){
var inc=$(this);
$.get(inc.attr("title"), function(data){
inc.replaceWith(data);
});
});
Please note that banner.html should be located under the same domain your other pages are in otherwise your webpages will refuse the banner.html file due to Cross-Origin Resource Sharing policies.
Also, please note that if you load your content with JavaScript, Google will not be able to index it so it's not exactly a good method for SEO reasons.
Web Components
I create following web-component similar to JSF
<ui-include src="b.xhtml"><ui-include>
You can use it as regular html tag inside your pages (after including snippet js code)
customElements.define('ui-include', class extends HTMLElement {
async connectedCallback() {
let src = this.getAttribute('src');
this.innerHTML = await (await fetch(src)).text();;
}
})
ui-include { margin: 20px } /* example CSS */
<ui-include src="https://cors-anywhere.herokuapp.com/https://example.com/index.html"></ui-include>
<div>My page data... - in this snippet styles overlaps...</div>
<ui-include src="https://cors-anywhere.herokuapp.com/https://www.w3.org/index.html"></ui-include>
None of these solutions suit my needs. I was looking for something more PHP-like. This solution is quite easy and efficient, in my opinion.
include.js ->
void function(script) {
const { searchParams } = new URL(script.src);
fetch(searchParams.get('src')).then(r => r.text()).then(content => {
script.outerHTML = content;
});
}(document.currentScript);
index.html ->
<script src="/include.js?src=/header.html">
<main>
Hello World!
</main>
<script src="/include.js?src=/footer.html">
Simple tweaks can be made to create include_once, require, and require_once, which may all be useful depending on what you're doing. Here's a brief example of what that might look like.
include_once ->
var includedCache = includedCache || new Set();
void function(script) {
const { searchParams } = new URL(script.src);
const filePath = searchParams.get('src');
if (!includedCache.has(filePath)) {
fetch(filePath).then(r => r.text()).then(content => {
includedCache.add(filePath);
script.outerHTML = content;
});
}
}(document.currentScript);
Hope it helps!
Here is a great article, You can implement common library and just use below code to import any HTML files in one line.
<head>
<link rel="import" href="warnings.html">
</head>
You can also try Google Polymer
To get Solution working you need to include the file csi.min.js, which you can locate here.
As per the example shown on GitHub, to use this library you must include the file csi.js in your page header, then you need to add the data-include attribute with its value set to the file you want to include, on the container element.
Hide Copy Code
<html>
<head>
<script src="csi.js"></script>
</head>
<body>
<div data-include="Test.html"></div>
</body>
</html>
... hope it helps.
There are several types of answers here, but I never found the oldest tool in the use here:
"And all the other answers didn't work for me."
<html>
<head>
<title>pagetitle</title>
</head>
<frameset rows="*" framespacing="0" border="0" frameborder="no" frameborder="0">
<frame name="includeName" src="yourfileinclude.html" marginwidth="0" marginheight="0" scrolling="no" frameborder="0">
</frameset>
</html>

Web Component / HtmlElement : unit testing

I'm trying to test a web component.
Here is my project structure :
├── package.json
├── src
│   ├── app.js
│   └── index.html
└── test
└── hello-world-test.html
Here is my working code :
class HelloWorld extends HTMLElement {
connectedCallback () {
this.innerHTML = 'Hello, World!'
}
}
customElements.define('hello-world', HelloWorld);
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script src="app.js"></script>
</head>
<body>
<hello-world></hello-world>
</body>
</html>
I'm trying to test that web component with web-component-tester.
I installed the utility globally :
npm install -g web-component-tester
I declared it in the package.json file :
"devDependencies": {
"web-component-tester": "^6.9.0"
}
then, I wrote my test in the test folder and saved it to hello-world-test.html:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script src="../node_modules/web-component-tester/browser.js"></script>
<script src="app.js"></script>
</head>
<body>
<test-fixture id="hello-world-fixture">
<hello-world></hello-world>
</test-fixture>
<script>
suite('<hello-world>', function(){
let component = document.querySelector('hello-world');
test('contains hello world string ?', () => {
let index = component.innerText.indexOf('Hello');
assert.isAtLeast(index, 0);
});
});
</script>
</body>
</html>
Finally, I typed :
wct --npm
Then obtained the following error in Chrome :
What am I missing to run the test correctly ?
The only decent materials I've found are this one and that one but they are outdated.
There are many errors :
First, please read the whole documentation as in the last paragraph it's clear that for those who use npm you need an additional dependency through the wctPackageName :
Components which wish to support npm-based installation should include
wct-browser-legacy in their devDependencies, which is a package that
contains only the client-side javascript necessary for executing WCT
tests in an npm-based environment. WCT will attempt to identify which
package provides the client-side code by checking for compatible
packages in the following order of preference: wct-mocha,
wct-browser-legacy and web-component-tester. If you want to specify
which package provides WCT client-side code, use the
--wct-package-name flag or wctPackageName option in wct.conf.json with the npm package name.
So you will need to add wct-browser-legacy in your devDependencies
Giving your project structure, you are including the app.js as if it was at the same level. It should be ../src/app.js.
You should add the type="module" to that import
You declared a fixture but didn't take profit of it through the function fixture
If I had to correct your code :
The command should be wct --npm -wct-package-name=wct-browser-legacy. Or even better create a wct.conf.js file with the following information :
module.exports = {
npm:true,
verbose: true,
plugins: {
local: {
browsers: ["chrome"]
}
},
wctPackageName: "wct-browser-legacy"
};
Your test should be modified as following :
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script src="../node_modules/web-component-tester/browser.js"></script>
<script src="../src/app.js"></script>
</head>
<body>
<test-fixture id="helloWorldFixture">
<template>
<hello-world>
</hello-world>
</template>
</test-fixture>
<script>
suite('<hello-world>', () => {
let component;
setup(() => {
component = fixture('helloWorldFixture');
});
test('contains hello world string ?', () => {
let index = component.innerText.indexOf('Hello');
assert.isAtLeast(index, 0);
});
});
</script>
</body>
</html>
Please, notice that I used the fixture's id and put the component initialisation in the setup function.
Zakaria's answer is good, but I suggest ditching wct-browser-legacy in favor of wct-mocha as it is lighter-weight and doesn't have out-of-date dependencies like old version of lodash and sinon etc.
See the README for full details: https://www.npmjs.com/package/wct-mocha
tl;dr version:
$ npm rm --save wct-browser-legacy
$ npm install --save-dev \
#webcomponents/webcomponentsjs \
#polymer/test-fixture \
wct-mocha \
mocha \
chai
You shouldn't need to specify it, but if you have wct.conf.js file you should change an existing wctPackageName entry to:
wctPackageName: "wct-mocha"
Your HTML needs to change a little and you need to make sure mocha is a direct dependency, since wct-mocha will not autoload. You'd also need to do that with chai if you're using chai assertions and #polymer/test-fixture if you use those.
<head>
<meta charset="utf-8">
<script src="../node_modules/#webcomponents/webcomponentsjs/webcomponents-loader.js"></script>
<script src="../node_modules/mocha/mocha.js"></script>
<script src="../node_modules/chai/chai.js"></script>
<script src="../node_modules/#polymer/test-fixture/test-fixture.js"></script>
<script src="../node_modules/wct-mocha/wct-mocha.js"></script>
</head>

Checking the internet connection and reading the files on/off line [duplicate]

I am linking to the jQuery Mobile stylesheet on a CDN and would like to fall back to my local version of the stylesheet if the CDN fails. For scripts the solution is well known:
<!-- Load jQuery and jQuery mobile with fall back to local server -->
<script src="http://code.jquery.com/jquery-1.6.3.min.js"></script>
<script type="text/javascript">
if (typeof jQuery == 'undefined') {
document.write(unescape("%3Cscript src='jquery-1.6.3.min.js'%3E"));
}
</script>
I would like to do something similar for a style sheet:
<link rel="stylesheet" href="http://code.jquery.com/mobile/1.0b3/jquery.mobile-1.0b3.min.css" />
I am not sure if a similar approach can be achieved because I am not sure whether the browser blocks in the same way when linking a script as it does when loading a script (maybe it is possible to load a stylesheet in a script tag and then inject it into the page) ?
So my question is: How do I ensure a stylesheet is loaded locally if a CDN fails ?
One could use onerror for that:
<link rel="stylesheet" href="cdn.css" onerror="this.onerror=null;this.href='local.css';" />
The this.onerror=null; is to avoid endless loops in case the fallback it self is not available. But it could also be used to have multiple fallbacks.
However, this currently only works in Firefox and Chrome.
Update: Meanwhile, this seems to be supported by all common browsers.
Not cross-browser tested but I think this will work. Will have to be after you load jquery though, or you'll have to rewrite it in plain Javascript.
<script type="text/javascript">
$.each(document.styleSheets, function(i,sheet){
if(sheet.href=='http://code.jquery.com/mobile/1.0b3/jquery.mobile-1.0b3.min.css') {
var rules = sheet.rules ? sheet.rules : sheet.cssRules;
if (rules.length == 0) {
$('<link rel="stylesheet" type="text/css" href="path/to/local/jquery.mobile-1.0b3.min.css" />').appendTo('head');
}
}
})
</script>
Assuming you are using the same CDN for css and jQuery, why not just do one test and catch it all??
<link href="//ajax.googleapis.com/ajax/libs/jqueryui/1/themes/start/jquery-ui.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jqueryui/1/jquery-ui.min.js"></script>
<script type="text/javascript">
if (typeof jQuery == 'undefined') {
document.write(unescape('%3Clink rel="stylesheet" type="text/css" href="../../Content/jquery-ui-1.8.16.custom.css" /%3E'));
document.write(unescape('%3Cscript type="text/javascript" src="/jQuery/jquery-1.6.4.min.js" %3E%3C/script%3E'));
document.write(unescape('%3Cscript type="text/javascript" src="/jQuery/jquery-ui-1.8.16.custom.min.js" %3E%3C/script%3E'));
}
</script>
I guess the question is to detect whether a stylesheet is loaded or not. One possible approach is as follows:
1) Add a special rule to the end of your CSS file, like:
#foo { display: none !important; }
2) Add the corresponding div in your HTML:
<div id="foo"></div>
3) On document ready, check whether #foo is visible or not. If the stylesheet was loaded, it will not be visible.
Demo here -- loads jquery-ui smoothness theme; no rule is added to stylesheet.
this article suggests some solutions for the bootstrap css
http://eddmann.com/posts/providing-local-js-and-css-resources-for-cdn-fallbacks/
alternatively this works for fontawesome
<link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet">
<script>
(function($){
var $span = $('<span class="fa" style="display:none"></span>').appendTo('body');
if ($span.css('fontFamily') !== 'FontAwesome' ) {
// Fallback Link
$('head').append('<link href="/css/font-awesome.min.css" rel="stylesheet">');
}
$span.remove();
})(jQuery);
</script>
You might be able to test for the existence of the stylesheet in document.styleSheets.
var rules = [];
if (document.styleSheets[1].cssRules)
rules = document.styleSheets[i].cssRules
else if (document.styleSheets[i].rules)
rule= document.styleSheets[i].rules
Test for something specific to the CSS file you're using.
Here's an extension to katy lavallee's answer. I've wrapped everything in self-executing function syntax to prevent variable collisions. I've also made the script non-specific to a single link. I.E., now any stylesheet link with a "data-fallback" url attribute will automatically be parsed. You don't have to hard-code the urls into this script like before. Note that this should be run at the end of the <head> element rather than at the end of the <body> element, otherwise it could cause FOUC.
http://jsfiddle.net/skibulk/jnfgyrLt/
<link rel="stylesheet" type="text/css" href="broken-link.css" data-fallback="broken-link2.css">
.
(function($){
var links = {};
$( "link[data-fallback]" ).each( function( index, link ) {
links[link.href] = link;
});
$.each( document.styleSheets, function(index, sheet) {
if(links[sheet.href]) {
var rules = sheet.rules ? sheet.rules : sheet.cssRules;
if (rules.length == 0) {
link = $(links[sheet.href]);
link.attr( 'href', link.attr("data-fallback") );
}
}
});
})(jQuery);
Do you really want to go down this javascript route to load CSS in case a CDN fails?
I haven't thought all the performance implications through but you're going to lose control of when the CSS is loaded and in general for page load performance, CSS is the first thing you want to download after the HTML.
Why not handle this at the infrastructure level - map your own domain name to the CDN, give it a short TTL, monitor the files on the CDN (e.g. using Watchmouse or something else), if CDN fails, change the DNS to backup site.
Other options that might help are "cache forever" on static content but there's no guarantee the browser will keep them of course or using the app-cache.
In reality as someone said at the top, if your CDN is unreliable get a new one
Andy
Look at these functions:
$.ajax({
url:'CSS URL HERE',
type:'HEAD',
error: function()
{
AddLocalCss();
},
success: function()
{
//file exists
}
});
And here is vanilla JavaScript version:
function UrlExists(url)
{
var http = new XMLHttpRequest();
http.open('HEAD', url, false);
http.send();
return http.status!=404;
}
if (!UrlExists('CSS URL HERE') {
AddLocalCss();
}
Now the actual function:
function AddLocalCss(){
document.write('<link rel="stylesheet" type="text/css" href=" LOCAL CSS URL HERE">')
}
Just make sure AddLocalCss is called in the head.
You might also consider using one of the following ways explained in this answer:
Load using AJAX
$.get(myStylesLocation, function(css)
{
$('<style type="text/css"></style>')
.html(css)
.appendTo("head");
});
Load using dynamically-created
$('<link rel="stylesheet" type="text/css" href="'+myStylesLocation+'" >')
.appendTo("head");
Load using dynamically-created <style>
$('<style type="text/css"></style>')
.html('#import url("' + myStylesLocation + '")')
.appendTo("head");
or
$('<style type="text/css">#import url("' + myStylesLocation + '")</style>')
.appendTo("head");
I'd probably use something like yepnope.js
yepnope([{
load: 'http:/­/ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js',
complete: function () {
if (!window.jQuery) {
yepnope('local/jquery.min.js');
}
}
}]);
Taken from the readme.
//(load your cdn lib here first)
<script>window.jQuery || document.write("<script src='//me.com/path/jquery-1.x.min.js'>\x3C/script>")</script>

How to implement custom filters in Polymer 1.7.x

I am trying to implement a custom filter using Polymer v1.7.0 currently. However, it does not work at all; when I try to use a filter the output is just the raw expression, unprocessed.
I have tried it like it's done here: https://github.com/PolymerLabs/polymer-patterns/blob/master/snippets/filters/using-custom-filters.html but using this code:
<div id="toFixed">{{10.123456789 | toFixed(2)}}</div>
only results in
{{10.123456789 | toFixed(2)}} in the resulting document.
Is my linked source outdated? I couldn't find any valuable information in the Polymer docs so a nudge into the right the direction is appreciated.
You don't need pipe in Polymer 1.x to achieve this. You can directly call an function and pass it the value that you want to
<base href="https://polygit.org/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link rel="import" href="polymer/polymer.html">
<dom-module id="my-element">
<template>
{{format(myVal)}}
<br>{{format("hello")}}
</template>
</dom-module>
<script>
Polymer({
is: "my-element",
properties: {
myVal: {
type: String,
value: "Hi"
}
},
format: function(input) {
return input + " John";
}
});
</script>
<my-element></my-element>

Trying to get import to work

Inspired by this html5rocks post, I thought I'd try link rel="import".
In the console, I get:
yay!
Loaded import: http://www.example.com/HelloWorld.htm
But I don't get "Hello World!" on the page.
Here's my code:
<!DOCTYPE html>
<html>
<body>
<script>
function supportsImports() {
return 'import' in document.createElement('link');
}
if (supportsImports()) {
console.log('yay!')
} else {
console.log('boo!')
}
function handleLoad(e) {
console.log('Loaded import: ' + e.target.href);
}
function handleError(e) {
console.log('Error loading import: ' + e.target.href);
}
</script>
<link rel="import" href="HelloWorld.htm" onload="handleLoad(event)" onerror="handleError(event)">
</body>
</html>
And HelloWorld.htm contains:
<h1>Hello World!</h1>
Edit:
In the console, I can see that <h1>Hello World!</h1> is inside the link tag as another #document, complete with <html><head></head></body>.
According to the same HTML5Rocks post, when you import an HTML resource, it is accessible as a JavaScript object. Specifically, a Document:
var myImport = document.querySelector('link[rel="import"]').import;
document.querySelector(/* get the element we want here */).appendChild(myImport.body);
That does contradict somewhat with the beginning of the article, which balks at using JavaScript to load HTML, but at least it uses much less JavaScript (the kind that can, perhaps, fit in a browser tag) and certainly is not subject to the CORS restrictions that AJAX has to deal with.