如何获取网页 HTML 可用的所有 JavaScript 功能？

Question

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.com/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.com/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?

Answer 1

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>