How do i get the url of a javascript file?

Even easier than using an id is to just leave the markup alone and use document.currentScript. The link to MDN mentions under the Notes section, a small quirk requiring the JavaScript to execute synchronously, and I'm about to explain how to avoid this pitfall.

It's important to note that this will not reference the element if the code in the script is being called as a callback or event handler; it will only reference the element while it's initially being processed.

The advantage of this solution is that you are not required to use special markup, and this is especially helpful if you can't access the HTML yourself for some reason [e.g. if it's used by a client or a developer using your API].

If the script is executed synchronously [meaning the main content of the script isn't wrapped in an event listener or some other function set to evaluate later than when the code is "initially being processed" ], you can simply use document.currentScript to access the currently processing element of your code. To demonstrate how to use this effectively, I'll provide a basic demo below.

HTML:

JavaScript in //bla.com/js/script.js:

var myScript = document.currentScript,
    mySrc = myScript.getAttribute['src'];

console.log[mySrc]; // "//bla.com/js/script.js"

$[function [] {
    // your other code here, assuming you use jQuery
    // ...
}];

If you don't want the variable to be exposed to the global scope, you can also do this:

[function [] {
    var myScript = document.currentScript,
        mySrc = myScript.getAttribute['src'];

    console.log[mySrc]; // "//bla.com/js/script.js"

    $[function [] {
        // your other code here
        // ...
    }];
}[]]; // self-executing anonymous function

Basically the point is to make sure and access document.currentScript during synchronous execution of the script, otherwise it will not reference what you expect it to.

This snippet will get the filename from the url. The filename is the last part of the URL from the last trailing slash. For example, if the URL is //www.example.com/dir/file.html then file.html is the file name.

Explanation

var url = window.location.pathname;

This declares the url variable and adds the current pathname as its value.

var filename = url.substring[url.lastIndexOf['/']+1];
alert[filename];

substring [method] - extract characters from start [parameter]. url is the stringObject url.substring[start]

lastIndexOf [method] - position of last occurrence of specified string value, in this case the ‘/’

Add one to lastIndexOf because we do not want to return the ‘/’

Full snippet

var url = window.location.pathname;
var filename = url.substring[url.lastIndexOf['/']+1];
alert[filename];

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