Loop through array in JavaScript - Stack Overflow

var myStringArray = ["Hello","World"];
var arrayLength = myStringArray.length;
for (var i = 0; i < arrayLength; i++) {
    alert(myStringArray[i]);
    //Do something
}

iterating arrays for-in should be avoided, that statement is meant to enumerate object properties.
It shouldn't be used for array-like objects because:

• The order of iteration is not guaranteed, the array indexes may not visited in the numeric order.
• Inherited properties are also enumerated.

The second point is can give you a lot of problems, for example, if you extend the Array.prototype object to include a method there, that property will be also enumerated.
For example:

Array.prototype.foo = "foo!";  var array = ['a', 'b', 'c'];    for (var i in array) {    alert(array[i]);  }

The above code will alert, "a", "b", "c" and "foo!".
That be particularly a problem if you use some library that relies heavily on native prototypes augmention (such as MooTools for example).
The for-in statement as I said before is there to enumerate object properties

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