I'd like to use socket.io in a javascript file. How can I do this?
The only way I currently know of using socket.io, as a client is doing
<script src="[server?]/socket.io/socket.io.js"></script> inside an html file.
Including a javascript within a javascript file is not naturally accomplished, because it's not really needed in most scenarios (you just include them both on your html page, for example). You probably have to rethink the way you're executing javascript, but I do believe there is a library designed to this (for whatever reason that may be).
include.js I think it is called.
EDIT: and in the event you're thinking dynamically adding javascript, you can just create a script element and append it to document.head. Um, for example:
document.head = document.head || document.getElementsByTagName('head')[0];
var js = document.createElement('script');
js.setAttribute('type','text/javascript');
js.setAttribute('src','http://my/src/file');
document.head.appendChild(js);
...just off the top of my head.
In my html file I did:
<script src="http://[node server]:[port]/socket.io/socket.io.js"></script>
`
and in my .js file, I did
io.socket = io.connect('http://[node server]:[port]');
and it worked.
I suppose "a standalone javascript file" is inaccurate, because I'm building a web front-end. I meant that it was just a .js file with nothing like node.js running it.
Related
Is there anyway of importing multiple javascript files in HTML without having to specify each file?
<script src="js/toolkit/Toolkit.js"></script>
<script src="js/toolkit/Viewable.js"></script>
<script src="js/toolkit/Overlay.js"></script>
ie. can I specify something like js/toolkit/* ?
I have 50+ javascript files that i have to import, and to specify each file seems very time consuming.
Including a JavaScript file in another JavaScript file is common in web development.
Because many times we include the JavaScript file at run time on the behalf of some conditions.
So, we can achieve this using JavaScript as well as using jQuery.
Method 1: Use JavaScript to include another JavaScript file
Add the following function in your web page.
function loadScript(url)
{
var head = document.getElementsByTagName('head')[0];
var script = document.createElement('script');
script.type = 'text/javascript';
script.src = url;
head.appendChild(script);
}
just call the below loadScript function, where you want to include the js file.
loadScript('/js/jquery-1.7.min.js');
Method 2: Use jQuery to include another JavaScript file.
Add jQuery File in your webpage.
<script src="//code.jquery.com/jquery-1.11.2.min.js"></script>
Just call the getScript function functions.
jQuery(document).ready(function(){
$.getScript('/js/jquery-1.7.min.js');
});
How to include a JavaScript file in another JavaScript File
There's a way:
You can create a javascript function that takes the path as a parameter and creates these HTML lines:
<script src="js/toolkit/Toolkit.js"></script>
<script src="js/toolkit/Viewable.js"></script>
<script src="js/toolkit/Overlay.js"></script>
And you'll just have to call this:
loadLib("toolkit/Toolkit");
loadLib("toolkit/Viewable");
loadLib("toolkit/Overlay");
But this is not recommended because the load time will be increased due to the number of HTTP requests.
You should better use something in the server side to put everything in the same file.
No you can't do it. And by the way this is not good idea to load all 50 separate files. Consider compressing them in one single script to improve performance and decrease page load time.
You can setup grunt to watch the folder of the scripts and concat/minify them into a single file, then you just have to include that in your HTML file.
You will need to specify each file for the browser to know what to retrieve, but depending on the IDE you are using, there may be shortcuts for doing this, (Visual Studios allows you to drag and drop script files into the html to add references).
During development, you want to do just as your doing by keeping the files separate for troubleshooting, but in production, as others have commented, its very good practice to minify your code and combine them into one file. That makes it only one call, and can reduce your overhead significantly.
I recommend you to use JSCompress. It will compress all your javascript code into one single javascript file.
import "./angular.min.js"
import "./jquery-3.6.0.min.js"
import "./app.js"
<script type="module" src="js/importJS.js"></script>
I've seen quite a few questions regarding loading a .js file into an HTML file, and I know how to do that. However, say I have the file "classlist.js." How can I go about using the classes defined in that javascript file in another javascript file? I keep seeing answers that suggest using the
<script type="text/javascript" src="filepath"></script>
syntax. When used in a .js file, though, it throws a syntax error on the "<" so I assume this code is invalid.
So, how would one utilize a function in a .js file that was defined in a separate .js file... that works, and is efficient (If there is one)?
EDIT:
I'm going to clarify some thing for the future, since I'm still fairly new to Javascript, and it looks like there were a number of other factors I didn't even know came into play.
I had two .js files, one of which declared classes that were extensions of classes in the other file. I wanted to use the extended classes in a webpage, and I thought I had to load the originial classes into the second .js file, THEN load that .js file into the HTML file. I wasn't programming completely outside of HTML.
Sorry for any misunderstanding, hopefully this thread is helpful to somebody else in the future.
Assuming you are talking about javascript in a web browser, all js files are loading in an html file, typically index.html. You need to use the script tag to load the javascript in the proper order in that html file, not in the javascript file. So if file B requires the things in file A, you need to load file A first, meaning put the script tag that loads file A before the script tag that loads file B.
Two answers:
Non Browser
If you're using JavaScript in a non-browser environment (NodeJS, RingoJS, SilkJS, Rhino, or any of a bunch of others), the answer depends on the environment — but many of these use the CommonJS require mechanism. E.g.:
// Get access to public symbols in foo.js
var foo = require("foo.js");
// Use the `bar` function exported by foo.js
foo.bar();
Browser
If you're using JavaScript in a browser, you put script tags like the one you quoted in the HTML, in the order in which they should be processed (so, scripts relying on things defined in other scripts should be included after the scripts they rely on).
If you want to maximize efficiency in terms of page load time, combine the scripts together on the server (probably also minifying/compressing/packing them) and use just the one script tag.
The answers posted above should do the trick however since you mentioned doing it efficiently you can consider taking a look at javascript module based loaders like require js( http://requirejs.org/ ) based on AMD
You have to put the reference to classlist.js in your HTML file (not your Javascript file), before any other SCRIPT element which requires it. For example, within the 'head' element:
<html>
<head>
<script src="testclass.js"></script>
<script src="file_using_testclass.js"></script>
<script>
var tc = new TestClass();
</script>
</head>
A common pattern for loading backbone templates is something like:
<script type='text/template' id='foo'>
my template
</script>
----
var whatever = $('#foo').html();
I would like to include the script in an external file like so:
<script type='text/template' id='foo' src='myTemplate.tpl'></script>
But the html() of foo is now empty.
I watched the browser pull the template file down, but I am not sure if it is in the page dom or not. Is there a simple way to reference the content of the script in javascript, or did the browser simply ignore it and throw out the result?
I think to actually execute externally loaded script you have to do an eval() of the contents. You're not adding it to the DOM really since it's script, you're adding it to the JS runtime. There might be other ways of doing it but eval() is generally considered a security hole since malicious code could be evaluated.
What I tend to do is generate template sections on the server so I know all my JS is there when the DOM is ready.
If the point is execute an action just after the script has been loaded you can put a onload attribute on the script tag. If you want to download the content in runtime, then you could use the async download strategy (like Gats pointed).
It´s important keep in mind some important points when using templates for jquery templates in external files, there is an interesting article about jquery templates with external files, you must check it.
How do you load one JavaScript file from another JavaScript file, like CSS?
In CSS we use write #import url("mycss.css");.
Is there any way to do it in JavaScript?
There's no #import-ish function/method in Javascript, but you can simply append a script to the <head> tag like so:
var newScript = document.createElement('script');
newScript.type = 'text/javascript';
newScript.src = '/path/to/js/file';
document.getElementsByTagName('head')[0].appendChild(newScript);
Or like Edgar mentioned right before me you can use jQuery.
Yes. If you want in pure JavaScript, you have to create dynamically a script tag, and append it to the document.
Yes. If you use the jQuery library, you can use the $.getScript method.
$.getScript("another_script.js");
Just because no-one has mentioned it yet, there's another option, which doesn't require any fancy libraries or tricky coding, document.write. In principal, it would look like this, although see below for a caveat:
document.write('<script src="myscript.js" type="text/javascript"></script>');
This will be executed upon completely parsing the script tag, and if you put your script tag in the head, the new script tag will also be in the head, right after the one being executed. Take care to execute it directly rather than when the document has been loaded (as in a $(function(){}) callback. This is what I use:
(function(){
function load(script) {
document.write('<'+'script src="'+script+'" type="text/javascript"><' + '/script>');
}
load("script1.js");
load("script2.js");
load("etc.js");
})();
The enclosing function is just there to not pollute the global namespace.
The caveat (and why the 'script' that is broken up above) is that there may be no ending script tags within a script tag, the HTML parser doesn't know it's part of the script. There's an other question on that subject.
Javascript itself doesn't provide any help with modularization other than the ability to eval a string. But this is a common-enough need that most big javascript frameworks have come up with their own solutions, and more recently, there has been an effort to standardize those APIs in the requirejs project. If you're using a framework like Dojo or jQuery, you're probably just best off learning to use their facilities, but if not, requirejs is a lightweight standalone tool. You basically just add
<script data-main="scripts/main" src="scripts/require.js"></script>
to your <head> section, and then put your own javascript inside some wrapper code like this (stolen from the require.js site):
require(["helper/util"], function() {
//This function is called when scripts/helper/util.js is loaded.
require.ready(function() {
//This function is called when the page is loaded
//(the DOMContentLoaded event) and when all required
//scripts are loaded.
});
});
use const dataName =require('./fileName.js');
I have created a string builder JavaScript object and I'm using it with many different .js files in my project.
Can I create this class in a separate .js file and call it from all the other scripts that instansiate it, just like a C# class file?
Is this possible, or do I continue copying and pasting it into the bottom of every .js file that uses it?
Yes, this should not be a problem. Just include the .js files in the correct order in your html pages.
If you include the file in your main HTML page with your other js, you can then use the "class" as you wish:
<script src="js1.js" type="text/javascript"></script>
<script src="js2.js" type="text/javascript"></script>
In the above example, you can now instantiate a new instance of an object from js1.js with the code in js2.js. To do this with pure javascript, you would have to add the script tag to the DOM, or use AJAX to fetch the script file and eval() it.
// Create a <script> element
var scriptEl = document.createElement("script");
scriptEl.src = "js2.js";
scriptEl.type = "text/javascript";
// Append it to the <head>
document.getElementsByTagName("head")[0].appendChild(scriptEl);
To be perfectly correct, it's not the order of inclusion that matter, but rather the order of executing code. In most cases, Andy's and Segfault's instructions are just fine, but sometimes including the class file before its consumers isn't sufficient. For example, if you use ExtJS and you happen to define your class inside an onReady handler like this:
Ext.onReady(function() {
myClass = ...
}.bind(this));
then it won't get executed by the time your second src file is included into the page and executed.
I know, the example is a bit far-fetched :) but just make sure that your code is executed in the right order, not just included in the right order.
I came across this question and I wanted to add something (which probably wasn't there a few years ago).
Even thought you can add every single script to your "index.html" it's not a very beautiful practice (imho). Especially if you consider that you may want to write a extension (~ framework). You don't want to annoy the user with a bunch of script tags he has to add to his code. What you want is a single line like this:
<script src="yourFramework" (...) />
However, with the use of RequireJS you are able to achieve this. You've the freedom to separate your code and "your user" still don't have to add a novel to his "script section".