Where can I get info on the object parameter syntax for JavaScript functions?

Question

If I want to call a function like this:

moo({ a: 4 });

Normally I'd have to phrase my function definition like this:

function moo(myArgObj) {
    print(myArgObj.a);
}

But this awesome syntax is totally valid in spidermonkey for defining functions:

function moo({ a, b, c }) { // valid syntax!
    print(a); // prints 4
}

What is this feature?

Answer 1

It's called destructuring. You might find the most info at MDN: Destructuring assignment (especially see Unpacking fields from objects passed as function parameter).

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The ECMAScript standards discussion can be found on their wiki page, also interesting might be this blog post at dailyjs.