How do I get query string value from script path?

Since there is no more significant use of Internet Explorer. You can use document.currentScript and new URL, which return a string with the tag <script> in question.

const search            = new URL(document.currentScript.src).search.substring(1)
const stringPreparation = decodeURI(search).replace(/"/g, '\\"').replace(/&/g, '","').replace(/=/g, '":"')
const qs                = JSON.parse('{"' + stringPreparation + '"}')

You can reduce this code to one line, but it is not recommended, let minifier scripts do that.

You can use the URL api and document.currentScript to retreive this`

const url = new URL(document.currentScript.getAttribute('src'));
const scriptParams = Object.fromEntries(url.searchParams)
console.log(scriptParams);

This is possible. See Passing JavaScript arguments via the src attribute. The punchline is that since scripts in HTML (not XHTML) are executed as loaded, this will allow a script to find itself as it is always the last script in the page when it’s triggered–

var scripts = document.getElementsByTagName('script');
var index = scripts.length - 1;
var myScript = scripts[index];
// myScript now contains our script object
var queryString = myScript.src.replace(/^[^\?]+\??/,'');

Then you just apply the query string parsing.

First, the technical answer: if you assign your script tag an ID, you can then grab its src and then parse out the query string.

<script id="whatever" type="text/javascript" src="file.js?abc=123"></script>

 

var path = document.getElementById('whatever').src;
// ...

With that answered, I'd like to voice my concern — this reeks of poor design decisions. Why are you including your script this way (with a querystring)? If you're trying to optimize your site (by having one large script that can be cached for subsequent pages), this approch is actually counter-productive because browsers will make a fresh request for the script file on each page due to the differing query string. The correct approach is to have one large shared file and then a small page-specific file on each page.