Doesn't JavaScript support closures with local variables?
closures, javascript, loops
Solution
Fixed Jon's answer by adding an additional anonymous function:
function create() {
for (var i = 0; i < 5; i++) {
closures[i] = (function(tmp) {
return function() {
alert("i = " + tmp);
};
})(i);
}
}
The explanation is that JavaScript's scopes are function-level, not block-level, and creating a closure just means that the enclosing scope gets added to the lexical environment of the enclosed function.
After the loop terminates, the function-level variable `i` has the value `5`, and that's what the inner function 'sees'.
As a side note: you should beware of unnecessary function object creation, espacially in loops; it's inefficient, and if DOM objects are involved, it's easy to create circular references and therefore introduce memory leaks in Internet Explorer.
Problem
I am very puzzled about this code: ``` var closures = []; function create() { for (var i = 0; i < 5; i++) { closures[i] = function() { alert("i = " + i); }; } } function run() { for (var i = 0; i < 5; i++) { closures[i](); } } create(); run(); ``` From my understanding it should print `0,1,2,3,4` (isn't this the concept of closures?). Instead it prints `5,5,5,5,5`. I tried Rhino and Firefox. Could someone explain this behavior to me?