I am wondering whether it is possible to get all the JavaScript functions that are included in the HTML. For example, if my HTML includes the following:

<script src=".js"></script>
<script>
  function foo() {}
  function bar() {}
</script>

How do I use JavaScript to retrieve all the JS functions available to this webpage. In this case, I would need to retrieve foo, bar and all the functions defined in .js. Doing document.getElementsByTagName("script"); only returns the scripts as HTML objects, but I need to get all the functions for each script included in the HTML. Can this be done?

I am wondering whether it is possible to get all the JavaScript functions that are included in the HTML. For example, if my HTML includes the following:

<script src="https://www.example./script.js"></script>
<script>
  function foo() {}
  function bar() {}
</script>

How do I use JavaScript to retrieve all the JS functions available to this webpage. In this case, I would need to retrieve foo, bar and all the functions defined in https://www.example./script.js. Doing document.getElementsByTagName("script"); only returns the scripts as HTML objects, but I need to get all the functions for each script included in the HTML. Can this be done?

• javascript
• html
• dom

Share Follow asked Dec 5, 2020 at 2:18 Mark NibuhMark Nibuh 4111 silver badge22 bronze badges 1

• "Can this be done?" Yes, but it is extremely hard to do so. You'd need to get all of the script tags' innerHTML if it has no src, but if it does, you'd need to use fetch() with that url and get the text response. One you get all of that, you'd need a JS parser to find every single function declaration and modifications to window. – Samathingamajig Commented Dec 5, 2020 at 2:30

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1 Answer 1

Sorted by: Reset to default 5

You could iterate on the window object and detect all functions like this:

var list = [];
for (let i in window) {
    if (typeof(window[i]) === "function")
        list.push(i);
}
console.log(list)

By doing this around your script, we can detect functions that were added in-between.

<script>
var list1 = [];
for (let i in window) {
    if (typeof(window[i]) === "function")
        list1.push(i);
}
</script>

<script>
// The script to measure
function newFunction() {}
</script>

<script>
var list2 = [];
for (let i in window) {
    if (typeof(window[i]) === "function")
        list2.push(i);
}
let functionList = list2.filter((item) => {return list1.indexOf(item) == -1})
console.log(functionList.join(" "));
</script>