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

The choice should be based on the which idiom is best understood.

An array is iterated using:

for (var i = 0; i < a.length; i++)
   //do stuff with a[i]

An object being used as an associative array is iterated using:

for (var key in o)
  //do stuff with o[key]

Unless you have earth shattering reasons, stick to the established pattern of usage.