JavaScript for…in vs for

Question

Do you think there is a big difference in for...in and for loops? What kind of \"for\" do you prefer to use and why?

Let\'s say we have an array of associative array

Answer 1

Updated answer for 2012 current version of all major browsers - Chrome, Firefox, IE9, Safari and Opera support ES5's native array.forEach.

Unless you have some reason to support IE8 natively (keeping in mind ES5-shim or Chrome frame can be provided to these users, which will provide a proper JS environment), it's cleaner to simply use the language's proper syntax:

myArray.forEach(function(item, index) {
    console.log(item, index);
});

Full documentation for array.forEach() is at MDN.