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javascriptencapsulation

How to read the code behind standard JavaScript methods?

I have been Googling this, but I can't seem to find a way I can read the code behind standard JavaScript methods such as Object.prototype.toString() or Document.getElementsByTagName(). If no such method exists, is there any way to unwrap the internal complexity of a JavaScript object after it has been encapsulated?

Solution

  • For custom functions, you can actually call the toString() method to see the code. For example, on a page that has jQuery:

    >> $.toString()
"function (a,b){return new e.fn.init(a,b,h)}"

    But when you call:

    >> toString.toString()

    You get:

    "function toString() {
  [native code]
}"

    The native code is not written in JS, I'm guessing it's C++. You can see the source in the corresponding JS interpreter project, e.g. V8.