Avoid closure creation within a non-lexically scoped loop.

ideal.js

var idx = -1;
var end = 10;

function eventually(fn, timeout) {
  setTimeout(fn, timeout);
}

while (++idx < 10) {
  eventually(console.log.bind(console, idx));
}

will-not-work.js

for (var i=0; i<10; i++) {
  　setTimeout(function() {
  　　console.log(i);
  　}, i);
  })
}

working.js

for (var i=0; i<10; i++) {
  (function (i) {
    setTimeout(console.log.bind(console, i), i);
  })(i);
}

Should print:

0
1
2
3
4
5
6
7
8
9