用函数参数破坏分配

Question

function foo( [a,b] ) {

    console.log(a);
    console.log(b);
}

foo( [12,34] );

Prints:

12
34

Also here:

 var { a:x, b:y } = { a:7, b:8 };
 console.log(x); // prints: 7
 console.log(y); // prints: 8

Is this method of assignment valid? Will this method bring any problems?

Also using the same technique we can swap two variables:

var a = 1;
var b = 2;
[a,b] = [b,a];

I just wanted to know what problems will arise in future with this type of assignment? Where can I find the best reference relating to this type of assignments?

Answer 1

That is a Javascript 1.7 feature, it's part of the Mozilla implementation of Javascript.

https://developer.mozilla.org/en-US/docs/JavaScript/New_in_JavaScript/1.7#Destructuring_assignment_(Merge_into_own_page.2Fsection)

It is not part of any ECMAScript standard (as far as I am aware) and I don't think there are any plans to make it available in other browsers; you should not use this in portable websites.