HTML5 Contenteditable field and knockout: event rises before value binding [duplicate] - html

How can I bind an observable to an editable div text content?

You will need to modify the default "text" binding so that it is able to write the content of the edited div back to the observable. A simple custom binding handler for this task can look like this:
ko.bindingHandlers.editableText = {
init: function(element, valueAccessor) {
$(element).on('blur', function() {
var observable = valueAccessor();
observable( $(this).text() );
});
},
update: function(element, valueAccessor) {
var value = ko.utils.unwrapObservable(valueAccessor());
$(element).text(value);
}
};
But please note that this example code requires jQuery.
Usage is as simple as this:
<div contentEditable="true" data-bind="editableText: foo"></div>
Here is an example (written in CoffeeScript): http://jsfiddle.net/aBUEu/1/

You can't do that by default, because changing text in editable div won't raise any event that would update the value in your model.
You will need a custom binding for this. You can read about it here: http://knockoutjs.com/documentation/custom-bindings.html

Related

how to detect div value (Django rendered) change with MutationObserver

I am rendering a value from django backend to frontend, and I am trying to detect the div value change with MutationObserver. Below is my current code:
MutationObserver part:
window.addEventListener('load', function () {
var element = document.getElementById('myTaskList');
var MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
var observer = new MutationObserver(myFunction);
observer.observe(element, {
childList: true
});
function myFunction() {
console.log("this is a trial")
console.log(element);
console.log(element.innerHTML);
}
// setTimeout(function(){
// element.innerHTML = 'Hello World!';
// }, 1000);
//
// setTimeout(function(){
// element.innerHTML = 'Hello Space!';
// }, 2000);
});
html part:
<div hidden id="myTaskList">{{resultList | safe}}</div>
I am rendering a string "dummyValue" to the div, but just don't see the value from the console.log() statements inside function.
this works well when I uncomment the setTimeout functions though.
Thanks for any help on why MutationObserver won't detect the rendered div value
I finally figured out the reason. Hope this might be helpful for people having similar issues in the future.
So, basically I was using my Django form submit button to do two actions at one time:
1. submit data to the view and process the data in the view;
2. trigger another function with the click action through
Ajax.
The second action was blocked by the first action, and I was only able to get result from action 1.
My solution: I modified action 1 to use Ajax as well. As I mentioned above, I originally used the Django form to submit data. I trigger action 2 inside the success function of action 1. Everything is working well now.

Polymer. Way to dynamically add or remove observer

Is there a way to add or remove observer not in the moment of element initing?
I can define observer this way:
observers: ['dataChanged(data.*)']
Can i remove this observer later or can I set this observer different way than that?
You can easily add an observer dynamically, either by:
this._addObserverEffect("property", observerFunction);
or
this._addComplexObserverEffect("dataChanged(data.*)");
Removing is harder and Polymer does not provide a function to do this. Although you could search for it in the _propertyEffects array, I wouldn't recommend it. Maybe just check in your observer function whether it should still be active, and return if not.
you maybe can try this way:
configure your data property in the element with notify: true, so you can add a listener to changes with plain js
var element=document.querySelector("#YOUR-ELE-ID");
element.addEventListener("data-changed", function(e) {
//triggered when data property changes
});
https://www.polymer-project.org/1.0/docs/devguide/properties#notify
and to remove the bound listener you can call removeEventListener
https://developer.mozilla.org/de/docs/Web/API/EventTarget/removeEventListener
Example 1 - plain JS :
document.addEventListener('WebComponentsReady', function(e) {
var element=document.querySelector("#YOUR-ELE-ID");
element.addEventListener("data-changed", function(e) {
//triggered when data property changes
});
});
Example 2 - in custom element:
//...element definition...
ready: function() {
var element=document.querySelector("#YOUR-ELE-ID");
element.addEventListener("data-changed", function(e) {
//triggered when data property changes
});
}

getting the value of a code-mirror element

I am using the code-mirror component from the Polymer Designer, and can set the initial value, but cannot see how to get changes to the code from the user.
I initialise the code-mirror using
<code-mirror id="code_mirror" value="{{code}}">
</code-mirror>
and would like to listen for changes in {{code}}, but codeChanged doesn't seem to fire.
I know I can get the actual value using code_mirror.$.mirror.getValue(), but would like to use data-binding.
I have tried using on-change to no avail.
Assuming you're using https://github.com/PolymerLabs/code-mirror what you need to do is make the CodeMirror instance created in the ready handle some events that the instance itself is emitting, then make the code-mirror element fire any custom event (something which I know is called event relay)
The following example makes the polymer element fire the custom event code-change whenever the editor value is changed
ready: function() {
var me = this;
//...
this.mirror = CodeMirror(this.shadowRoot, { /* ... */ });
this.mirror.on('change', function () {
// me = polymer instance
me.fire('code-change', { value: me.mirror.getValue() })
});
}
Then any instance of the polymer custom element would need to listen to that event using Polymer's declarative event mapping or through addEventListener
1st case (if code-mirror is inside another <polymer-element />):
<code-mirror on-code-change="{{ onCodeChange }}"></code-mirror>
// ...
<script>
Polymer({
onCodeChange: function(event, detail, sender) { ... }
});
</script>
2nd case ():
<code-mirror></code-mirror>
<script>
document
.querySelector('code-mirror')
.addEventListener('code-change', function () { ... });
</script>

Adding properties for a Polymer element to observe based on content or a better way to handle forms

I need to create a form using the Polymer Paper-Input elements, and I need a way to know when all required content has been filled out.
I looked for a built in element, but didn't see one. So I wanted to create a polymer form element that would wrap all of the input tags. The resulting element would have an Invalid attribute which lets you know if any of the input tags are invalid.
The use of the tag would look like this:
<test-form id="testform">
<paper-input label="test" required error="This field is required"></paper-input>
</test-form>
Invalid: {{ $.testform.invalid }}
However, it appears that by the time in the elements lifecycle that I can loop over all the elements inside of the content tag, that anything added to the observe object is ignored.
Here is the code I was working on below:
<polymer-element name="test-form" attributes="invalid">
<template>
<content id="content">
</content>
</template>
<script>
Polymer('test-form', {
domReady: function () {
this.observe = {};
for (var i = 0; i < this.children.length; i++) {
this.observe["this.children[" + i + "].invalid"] = "valChanged";
}
},
invalid: false,
valChanged: function (oldValue, newValue) {
// TODO: If newValue is true set invalid to true
// If newValue is false, loop over all elements to see if all are now valid and invalid can be set to false.
alert("VALUE CHANGED" + oldValue + newValue);
}
});
</script>
Is there a better way to handle this or does anyone know how to make changes to what polymer is observing at this point in the lifecycle?
As far as checking the form's validity, you could simply check each form element's invalid property:
validate: function() {
var invalid = false;
Array.prototype.forEach.call(this.children, function(child) {
if (child.invalid === true) {
invalid = true;
}
});
this.invalid = invalid;
}
Then you could add an input event listener and run this method each time a form element's input changes.
Here's a working jsbin.
If I understand your question, your high level goal is form validation?
As has been detailed in polycasts and other places, I have used iron-form which has some very powerful validate() functionality, including what you mention above and much more.
It does sometimes require some odd usages of hidden <input> fields to get all of the work done, but this is easy to learn in the polycasts, such as polycast 55 and 56
If you stumbled upon this question in 2017, you would definitely now want to use more primitive tech, after you've seen what this has to offer.

jQuery datepicker won't work on a AJAX added html element

I have a jQuery datepicker function bound to the "birthday" input html element, written in the page header:
<script type="text/javascript">
$(function() {
$( "#birthday" ).datepicker();
});
</script>
Next, I have some AJAX functionality - it adds new input html element to the page. That element is:
<input type="text" id="birthday" value="" class="detail-textbox1" />
Clicking on that birthday element does not pop up the date picker below the text field. I expected this, as the element is added after the page is loaded, thus it isn't in relation with the function provided in the header.
How can I make it work? I tried moving the script from the header to the body, but nothing seems to work. Thanks.
P.S. If I create an input html element with id="birthday" in the page body, everythig works as expected. It appears that only the elements added through AJAX are dysfunctional.
I'm a bit late to the party, but for thoroughness - and with the .live() function being deprecated from jQuery 1.7 onwards - I thought I'd provide an updated solution based on my experiences, and from all the help I got from other answers on StackOverflow!
I had a situation where I needed to add the datepicker functionality to input fields that were being added to the DOM through AJAX calls at random, and I couldn't modify the script making the AJAX calls to attach the datepicker functionality, so I opted for the new shiny .on() function with its delegation features:
// do this once the DOM's available...
$(function(){
// this line will add an event handler to the selected inputs, both
// current and future, whenever they are clicked...
// this is delegation at work, and you can use any containing element
// you like - I just used the "body" tag for convenience...
$("body").on("click", ".my_input_element", function(){
// as an added bonus, if you are afraid of attaching the "datepicker"
// multiple times, you can check for the "hasDatepicker" class...
if (!$(this).hasClass("hasDatepicker"))
{
$(this).datepicker();
$(this).datepicker("show");
}
});
});
I hope this helps someone, and thanks for all the answers so far that led me to this solution that worked for me! :)
You need to use .live() so that any newly added elements have the event handler attached: http://api.jquery.com/live/
$('#birthday').bind('load', function() {
$(this).datepicker();
});
EDIT
.live() documentation states, that it is a bit out of date. With new versions of jquery (1.7+) use .on().
Boris, JK: This was super helpful for me. I have also found that you can use the following for AJAX html if you want to use Datepicker's date range selection:
$('#groundtransporation').live('focus', function() {
var gt = $( "#rentalPickUp, #rentalDropOff" ).datepicker({
defaultDate: "+1w",
changeMonth: true,
numberOfMonths: 2,
onSelect: function( selectedDate ) {
var option = this.id == "rentalPickUp" ? "minDate" : "maxDate",
instance = $( this ).data( "datepicker" ),
date = $.datepicker.parseDate(
instance.settings.dateFormat ||
$.datepicker._defaults.dateFormat,
selectedDate, instance.settings );
gt.not( this ).datepicker( "option", option, date );
}
});
});
I got another case.
My script is copying last table elements including datepicker.
The jquery will not working because the copied element has mark that it "hasDatepicker".
To activate datepicker in new element, remove that class name and the initiate it, like this.
$("#yournewelementid").attr("class","your-class-name");
$("#yournewelementid").datepicker();
your issue is always happens when elements don't exist when you try to initialize it.
When you use $(function(){/** some code **/}); elements must exsit on the document, it means that has to be on the html so you could can create a function to initialize the component or initialize it on the success event after been add it to the document.
Is important to first add the external html load in the ajax request to the document before you try to initialize it or it won't be initialize at all.
Example:
$.ajax({
url:"ajax_html.html",
dataType:"html"
}).done(function(html){
$("#selector").html(html)
init();
});
function init(){
$(".birthday").datepicker({});
}
You could initialize the date picker for the newly added element within your ajax success callback:
$.ajax({
...
success: function(response) {
if(response.success) {
$(body).append(response.html);
$("#birthday").datepicker();
}
}
});