JavaScript: clone a function
function, javascript
Solution
try this:
var x = function() {
return 1;
};
var t = function(a,b,c) {
return a+b+c;
};
Function.prototype.clone = function() {
var that = this;
var temp = function temporary() { return that.apply(this, arguments); };
for(var key in this) {
if (this.hasOwnProperty(key)) {
temp[key] = this[key];
}
}
return temp;
};
alert(x === x.clone());
alert(x() === x.clone()());
alert(t === t.clone());
alert(t(1,1,1) === t.clone()(1,1,1));
alert(t.clone()(1,1,1));
Problem
What is a fastest way to clone a function in JavaScript (with or without its properties)? Two options coming to mind are `eval(func.toString())` and `function() { return func.apply(..) }`. But I am worried about performance of eval and wrapping will make stack worse and will probably degrade performance if applied a lot or applied to already wrapped. `new Function(args, body)` looks nice, but how exactly can I reliable split existing function to args and body without a JS parser in JS? Update: What I mean is being able to do ``` var funcB = funcA.clone(); // where clone() is my extension funcB.newField = {...}; // without affecting funcA ```