JavaScript: clone a function

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Here is an updated answer

var newFunc = oldFunc.bind({}); //clones the function with '{}' acting as its new 'this' parameter

However .bind is a modern ( >=iE9 ) feature of JavaScript (with a compatibility workaround from MDN)

Notes

  1. It does not clone the function object additional attached properties, including the prototype property. Credit to @jchook

  2. The new function this variable is stuck with the argument given on bind(), even on new function apply() calls. Credit to @Kevin

function oldFunc() {
  console.log(this.msg);
}
var newFunc = oldFunc.bind({ msg: "You shall not pass!" }); // this object is binded
newFunc.apply({ msg: "hello world" }); //logs "You shall not pass!" instead
  1. Bound function object, instanceof treats newFunc/oldFunc as the same. Credit to @Christopher
(new newFunc()) instanceof oldFunc; //gives true
(new oldFunc()) instanceof newFunc; //gives true as well
newFunc == oldFunc; //gives false however

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