[a,b] = [b,a]
How does the above code swap a and b ?
I could see that the Right hand side of the expression crates an array, but I could not understand how it can be assigned to the left hand side.
Please see this fiddle http://jsfiddle.net/sethunath/MqWKH/
Update : Works only in firefox !
JavaScript 1.7 adds destructuring assignment, which you're observing there. JavaScript 1.7 is supported by few browsers. Notably, however, it is supported by Mozilla Firefox when the script tag has a type attribute of application/javascript;version=1.7.
The above code doesn't swap a and b, it will give you an
Invalid left-hand side in assignment
What do you want to do exactly? You can't, in Javascript, swap variables in this way!
Trying in browser:
[a,b] = [b,a]
Result:
ReferenceError: Invalid left-hand side in assignment
In other words: this isn't allowed in JavaScript.
CoffeeScript (which compiles to JavaScript) does, however.
var _ref = [b, a], a = _ref[0], b = _ref[1];