So what I'm trying to do is get text from a file in the same directory as my html file using JavaScript. I want to store an array inside a text file and change it whenever i want instead of constantly having to go into the code, save it, check if it works etc.
I've tried looking around but couldn't find any clear information, most of what I found is using .readAsBinaryString, etc..
I'm mostly seeing things like this but i can't seem find anything which is actually getting information from a textfile without making the person find the text file directory.
function storearray(newval){
var file = "file location;"
var txt = file.txt;
var array = txt.split("|");
txt = txt + newval + " | ";
return array;
}
To read a file from the user's disk you need to use FileReader and the user must explicitly select the file using a file input. (See JavaScript read file without using input).
To read a a file from the website you need to use Ajax (with fetch, XMLHttpRequest or a library that wraps around them like Axios). (See Using fetch from MDN).
If (as it seems here) you want to read data from the website but the website exists only on the user's disk then you still need to use Ajax but will usually run into security restrictions. Some browsers allow you to disable the security protection, but the general solution is to install a web server and load both HTML and the data file using HTTP.
Alternatively, you can store your data in JavaScript (you are generating an array from your text file, you can so that manually or have a build-time script do it) and just load it with a <script> element.
Related
I am building a web app and I would like to show PDF files to my users. My files are mainly stored as byte arrays in the database as they are generated in the backend. I am using the embed element and have found three ways to display a PDF:
Local file path in src attribute: Works, but I need to generate a file from the database byte array, which is not desirable as I have to manage routines to delete them once they are not needed anymore.
Online file path in src attribute: Not possible since my files may not be hosted anywhere but on the server. Also has the same issues as the previous method anyway.
Data as base64 string in src attribute: Current method, but I ran into a problem for larger files (>2MB). Edge and Chrome will not display a PDF when I covert a PDF of this size to a base64 string (no error but the docs reveal that there is a limit for the data in the src attribute). It works on Firefox but I cannot have my users be restricted to Firefox.
Is there any other way to transmit valid PDF data from a byte array out of the database without generating a file locally?
You have made the common mistake of thinking of URLs and file paths as the same thing; but a URL is just a string that's sent to the server, and some content is sent back. Just as you wouldn't save an HTML file to disk for every dynamic page on the site, you don't have to write to the file system to display a dynamic PDF.
So the solution to this is to have a script on your server that takes the identifier of a PDF in your system, maybe does some access checking, and outputs it to the browser.
For example, if you were using PHP, you might write the HTML with <embed src="/loadpdf.php?id=42"> and then in loadpdf.php would write something like this:
$pdfContent = load_pdf_from_database((int)$_GET['id']);
header('Content-Type: application/pdf');
echo $pdfContent;
Loading /loadpdf.php?id=42 directly in the browser would then render the PDF just the same as if it was a "real" file, and embedding it should work the same way too.
I would like to visualize data from csv file at node-red ui.
What I would like to do is to show behind a flag of a country the countity from the csv file. So into the csv file I have 2 columns (country, quantity).
Because of I am new at node-red I would like to get some hints how to do that.
Thanks in advance.
my flow with CSV data
Welcome to Node-RED!
Firstly you need to decide what kind of UI you would like. Node-RED has options for a number ranging from the creation of data driven web pages using the http-in/out and template nodes through the more dynamic but slightly more complex Dashboard through to full-power dynamic web-apps using things like node-red-contrib-uibuilder.
The very simplest approach is to use an http-in and an http-out node to define a web page. Then to add your file reader after the http-in then the CSV node (which turns the CSV data into JSON). Then you could use node-red-contrib-tableify to turn your JSON into an HTML table. Finally use the template node to insert the table into the html that the http-out node sends back to the browser.
http-in -> file read -> csv -> tablify -> template -> http-out
Once you've mastered that, you could go on either to smarten up the template or swap to using Dashboard or even uibuilder depending on your needs.
I have to create a web page first, right?
You define the URL in the http-in node. When the -in is connected to the -out, you have a "page". Albeit with no content. To create content you can use the template node. In fact, pushing the csv data through the tablify node and into the template would give you enough of a page to see the data. The templatate itself need only be:
<pre>{{payload}}</pre>
Though, of course, you can also wrap that with other HTML elements as needed. But that alone should be enough to render something useful.
How can I trigger the http-in?
You simply reference the URL from your browser. So if you set the http-in node to use URL /fred and you used a browser on the same device that is running Node-RED, you would use the URL http://localhost:1880/fred in your browser.
How should I design the web page to be able to put the information from the csv file into it by the http-out node?
The tablify node does that for you.
String together what I've outlined and you should see something that will let you go further.
I suggest just using http-in, template and http-out nodes to start so that you can see how they work together. Then feed in your data without the csv or tablify nodes, then add the csv and finally the tablify. That way you can see how things work.
I've never worked with web pages before and I'd like to know how best to automate the following through programming/scripting:
go to http://financials.morningstar.com/ratios/r.html?t=GMCR®ion=USA&culture=en_US
invoke the 'Export to CSV' button near the top right
save this file into local directory
parse file
Part 4 doesn't need to use the same language as for 1-3 but ideally I would like to do everything in one shot using one language.
I noticed that if I hover my mouse over the button it says: javascript:exportKeyStat2CSV(); Is this a java function I could call somehow?
Any suggestions are appreciated.
It's a JavaScript function, which is not Java!
At first glance, this may seem like you need to execute Javascript to get it done, but if you look at the source of the document, you can see the function is simply implemented like this:
function exportKeyStat2CSV(){
var orderby = SRT_keyStuts.getOrderFromCookie("order");
var urlstr = "//financials.morningstar.com/ajax/exportKR2CSV.html?&callback=?&t=XNAS:GMCR®ion=usa&culture=en-US&cur=&order="+orderby;
document.location = urlstr;
}
So, it builds a url, which is completely fixed, except the order by part, which is taken from a cookie. Then it simply navigates to that url by setting document.location. A small test shows you even get a csv file if you leave the order by part empty, so probably, you can just download the CSV from the base url that is in the code.
Downloading can be done using various tools, for instance WGet for Windows. See SuperUser for more possibilities. Anyway, 'step 1 to 3' is actually just a single command.
After that, you just need to parse the file. Parsing CSV files can be done using batch, and there are several examples available. I won't get into details, since you didn't provide any in your question.
PS. I'd check their terms of use before you actually implement this.
The button directs me to this link:
http://financials.morningstar.com/ajax/exportKR2CSV.html?&callback=?&t=XNAS:GMCR®ion=usa&culture=en-US&cur=&order=asc
You could use the Python 3 module urllib and fetch the file, save it using the os or shutil modules, then parse it using one of the many CSV parsing modules, or by making your own.
I am facing problem in HTML 5. I need to statically load data into web page from local saved files. Up to now, I have been only able to load data via < input type="file" id="fileinput" / > but I want to load data from static location, which never changes. How to do that? And is there any way how to determine, whether some local file was changed from previous version?
Thanks
no, this isn't possible if by 'local', you mean a file at /home/waypoint/somefile.txt. You can make a 'link' with the filesystem api (if you selected it in an input field, for instance), which is valid to do computations with it (to read it, write to it, display it in img,etc). But it is deleted/unvalid, as soon as the window closes. If you could just magically "read" any local file via javascript which resides on the file system, who would stop google to read out your /etc/passwd file?
if your local computer is also your server and therefor your server-side code has access to the local file /home/waypoint/somefile.txt, your app can get it via ajax. Checking if the file exists, would be done the same way.
I have a few HTML files that I'd like to include via tags in my webapp.
Within some of the files, I have pseudo-dynamic code - specially formatted bits of text that, at runtime, I'd like to be resolved to their respective bits of data in a MySQL table.
For instance, the HTML file might include a line that says:
Welcome, [username].
I want this resolved to (via a logged-in user's data):
Welcome, user#domain.com.
This would be simple to do in a JSP file, but requirements dictate that the files will be created by people who know basic HTML, but not JSP. Simple text-tags like this should be easy enough for me to explain to them, however.
I have the code set up to do resolutions like that for strings, but can anyone think of a way to do it across files? I don't actually need to modify the file on disk - just load the content, modify it, and output it w/in the containing JSP file.
I've been playing around with trying to load the files into strings via the apache readFileToString, but I can't figure out how to load files from a specific folder within the webapp's content directory without hardcoding it in and having to worry about it breaking if I deploy to a different system in the future.
but I can't figure out how to load files from a specific folder within the webapp's content directory without hardcoding it in and having to worry about it breaking if I deploy to a different system in the future.
If those files are located in the webcontent, use ServletContext#getRealPath() to convert a relative web path to an absolute disk file system path. This works if the WAR is exploded in the appserver (most does it by default, only Weblogic doesn't do that by default, but this is configureable IIRC). Inside servlets you can obtain the ServletContext by the inherited getServletContext() method.
String relativeWebappURL = "/html/file.html";
String absoluteFilePath = getServletContext().getRealPath(relativeWebappURL);
File file = new File(absoluteFilePath);
// ...
Alternatively, you can put it in the classpath of the webapplication and make use of ClassLoader#getResource():
String relativeClasspathURL = "/html/file.html";
URL absoluteClasspathURL = Thread.currentThread().getContextClassLoader().getResource(relativeClasspathURL);
File file = new File(absoluteClasspathURL.toURI());
// ...
As to the complete picture, I question if you have ever considered an existing templating framework like Freemarker or Velocity to ease all the job?