How to check if script done running

Question

I'm injecting programmatically some text-code into script, and I need to run some code only after the script is done running.

My code:

const InjectScript = (scriptContent) => {
  const script = document.createElement("script");
  script.type = "text/javascript";
  script.text = scriptContent;
  document.head.appendChild(script);

 //run some code after script executed
   someCode()
};

How can I check if the script is done running?

By the time `someCode()` runs your dynamically inserted javascript will already have executed (except any async code in it). — connexo, Sep 26 '21 at 12:55
Use promises in JavaScript it is what you are looking for see [MDN guide](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) — Sanmeet, Sep 26 '21 at 12:55
@Sanmeet Nothing async in the question, so no use for promises. — connexo, Sep 26 '21 at 12:56
@connexo I think the OP is looking for something async as it the above code doesn't needs anything more ! — Sanmeet, Sep 26 '21 at 12:58
Why do you even add a script tag with custom content instead of just running the code directly? (or is this a content script in a browser extension?) — CherryDT, Sep 26 '21 at 12:58
Fire an event from the dynamic script that `someCode` listens for. — morganney, Sep 26 '21 at 13:04
Please add information if the inserted script runs async code that you need to wait for. — connexo, Sep 26 '21 at 13:15
Attach to `window.someCode` then pass the name of the function to your dynamic script with `data-` attributes. — morganney, Sep 26 '21 at 13:16
Use `MutationObserver` and have `someCode` `observe` a node the dynamic script modifies. — morganney, Sep 26 '21 at 13:18

Emad Aljumaily · Answer 1 · 2021-09-26T12:59:22.587

-1

I think as like this

  var IsRunning = false;
  function myFunction() {
   if (!IsRunning) {
    IsRunning = true;
    }
    }

edited Sep 26 '21 at 12:59

answered Sep 26 '21 at 12:57

Emad Aljumaily

1
6

This is either not needed (if the inserted JS is not async), or useless (if it is). Aside from the fact that it is making use of global variables (which is generally frowned upon). – connexo Sep 26 '21 at 12:58

score -1 · Answer 2 · answered Sep 26 '21 at 13:03

-1

async await seems like the best choice if your runtime is okay with ECMAScript 2017 syntax, like so:

const InjectScript = async (scriptContent) => {
  const script = await document.createElement("script");
  script.type = await "text/javascript";
  script.text = await scriptContent;
  await document.head.appendChild(script);

  //run some code after script executed
  await someCode()
};

answered Sep 26 '21 at 13:03

John Hugh

11
2

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function – John Hugh Sep 26 '21 at 13:06
`appendChild` is not async so cannot be awaited, probably neither is `someCode` and it would not make a difference to await it anyway. – lawrence-witt Sep 26 '21 at 13:10
await is to ensure it runs in sequence, nothing to do with promises being compulsory. thanks for the feedback anyway – John Hugh Sep 26 '21 at 13:17
This does not prevent someCode from executing before the dynamic script finishes. – morganney Sep 26 '21 at 13:20

How to check if script done running

2 Answers2