Why does javascript turn array indexes into strings when iterating?
This Javascript logic puzzles me. I'm creating an array and setting the first element of it to a number. When I interate through it using a "for" loop Javascript turns the array key into a string. Why? I want it to stay a number.
stuff = [];
stuff[0] = 3;
for(var x in stuff) {
alert(typeof x);
}
It's because you're looping through the array using for...in which is generally used for looping over properties of objects. The javascript engine is probably casting to a string because the string type is suitable for names of object properties.
Try this more traditional approach:
stuff = [];
stuff[0] = 3;
for(var i=0; i<stuff.length; i++) {
var x = stuff[i];
alert(typeof x);
}
for..in is not designed to iterate over Arrays. Use a C-style for loop instead.
Reference: MDC
The for .. in loop in Javascript iterates through the properties of the object. In Javascript, property names are strings and arrays are just objects with a bunch of properties that happen to look like numbers.