CODEWITHSUNDEEP
javascriptfunctional-programming
madox2
madox2

Reputation: 51881

How can I compare functions which were bounded before in javascript?

How can I compare functions which were bounded before independently on context (this). I know that Function.prototype.bind returns new function but is it possible to find out reference to the original function? Let's say I want to implement function equalsOrigins to do it for me:

var func1 = someFunction.bind(obj1);
var func2 = someFunction.bind(obj2);
var func3 = otherFunction.bind(obj1);

func1 === func2; // naturally returns false
equalsOrigins(func1, func2); // should return true
equalsOrigins(func1, func3); // should return false
equalsOrigins(func2, func3); // should return false

Is that possible in javascript?

Upvotes: 3

Views: 116

Answers (1)

Bergi
Bergi

Reputation: 664970

Is it possible to find out reference to the original function?

No, not without access to the engine internals or a debugger. The bound function does contain a reference to the target function, but it is not accessible.

Your best bet, if the function does not throw or return an object, might be to abuse it as a constructor, and reconstruct the reference from the prototype object.

function example() { /* sane */ }
var bound = example.bind({});

Object.getPrototypeOf(new bound).constructor == example // true

Upvotes: 1

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