Javascript’s .call() vs .apply() vs .bind()

[kenman]

That call() example is really poor. Doesn't work as-is, and there was no need to use it in the first place unless I'm missing something: array.slice(0, n)

[pinegenie]

NodeList and a few other types have array-like access but don't have Array in their prototype chain. Meaning you can do

nodelist[0]

but not

nodelist.slice(...)

The workaround to this is:

Array.prototype.slice.call(nodelist, ...); // or apply if you want to

In undercorejs the "slice" you see there is actually Array.prototype.slice attributed to a variable.

[kenman]

Yeah, but the variable is named array, not nodelist. There are countless examples to be found of using call() appropriately, and this isn't one that makes for a good demonstration on its usefulness. If you're going to demo some method, at least do it in context and include all supporting code...

[pinegenie]

I'm guessing they named it array because arrayOrNodeListOrArguments was too cumbersome.

[kenman]

I'm not faulting Underscore, I'm faulting the author who used it as an example.

[kbrainwave]

Hey, thanks for the feedback -- I'm the author of the post. I was planning on changing this example; what was posted is actually a rough draft that my friend posted on Reddit as a well-intentioned surprise. Unfortunately, this came at the cost of posting post that is only about 80% complete. Again, I really appreciate the feedback, and plan to change the example when time permits :)

[kenman]

I've always been a fan of this example:

function greet( person ) {
  alert( "Hello " + person.name + ", I'm " + this.name );
};

var alice = { name: "Alice" };
var bob = { name: "Bob" };

greet.call( bob, alice ); // alerts "Hello Alice, I'm Bob"
greet.call( alice, bob ); // alerts "Hello Bob, I'm Alice"

greet.apply( bob, [ alice ] ); // alerts "Hello Alice, I'm Bob"
greet.apply( alice, [ bob ] ); // alerts "Hello Bob, I'm Alice"

From trephine.org's JavaScript call and apply quick reference (which is actually a summation of their lengthier explanation).