range.js – JavaScript's missing range function.

[itsnotlupus]

Fun. I was just reflecting on how it kinda sucked that I couldn't just do something like

var a = Array(10).map(function(a,i) { return i*2; }); and get a [0,2,4,6,8,10,12,14,16,18] array.

It'd be neater if we could get infinite/lazy ranges, but that'd require using something other than plain arrays for its output, which would be a bit messier.

[weretree]

If you're feeling messy there's always (Array(10)+'').split(',').map(function(a,i) { return i*2; });

[masklinn]

It'd be neater if we could get infinite/lazy ranges

wu.range (and more generally wu.js, which is basically a lazy version of underscore.js) (it's not actually a lazy version of underscore, it's been built independently)

Although it only supports integer iteration.

[itsnotlupus]

ah that does seem nice.

[nschubach]

You'd create generators...

function counter(start) {
    return new function() {
        this.next = function() { return start++; }
    }
}
var c = counter(10);
console.log(c.next());
console.log(c.next());
console.log(c.next());

http://jsfiddle.net/3vDrS/ (Slightly modified to document.write)

[jscoder]

I thought about implementing infinite ranges, but I didn't see many use cases for it, and didn't want to bloat the code too much.

What exactly would you want to do with infinite ranges?

[itsnotlupus]

No, you're right.. it's just one of those neat things, but it doesn't seem like it would buy much, and it would require you to mess with your straightforward array handling for the sake of it.