Function.prototype.bind behaviour (call vs apply)

Brendan Eich brendan at
Fri Aug 21 20:20:28 PDT 2009

On Aug 21, 2009, at 8:11 PM, Juriy Zaytsev wrote:

> If `boundArgs` is an array of arguments to bind, then I think you  
> should be able to do this via something like:
> Function.prototype.bind.apply(targetFn, [thisArg].concat(boundArgs));
> // or maybe:
> boundArgs.unshift(thisArg);
> Function.prototype.bind.apply(targetFn, boundArgs);
> Which is not very elegant of course (first version also takes a  
> performance hit by creating unnecessary Array object).

But it gets the job done.

I think it's better to leave ES5 Function.prototype.bind as specified,  
based on Prototype's bind (and others like it), which take positional  
arguments to partially apply.

Then with spread ( 
id=harmony:spread ) in Harmony, you can write  
foo.bind(thisArg, ...argsArray) instead of the above bind.apply  


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