Understanding JavaScript Arrays

[svnv]

Isn't this faster for iterating over the elements:

  var a = ["banana", Math.min, 4, "apple"];
  for (var i=a.length; i; i--) {
    console.log(a[i]);
  }

[svnv]

Actually, I just realized this does not work, there is an off by 1 error here. jacksoncarter's piece of code works though.

[jacksoncarter]

Or try this

  var i = a.length;
  while (i--){
    console.log(a[i]);
  }

[pooj]

Clever, but sometimes you don't want to go in reverse.

[code_duck]

Yes, in a micro-optimized way.

[ccollins]

I want to stress that the following will work, but get you in trouble. Javascript does not support associative arrays.

  var myData = new Array;

  myData['key1'] = 'value1';
  myData['key2'] = 'value2';
  myData['key3'] = 'value3';

  myData.length; //0

[olavk]

I would say that JS does support associative arrays, since it is the fundamental data type behind objects and arrays. Arrays are basically associative arrays, since the index is converted into a string and used as a key. E.g. myData[7] is equivalent to myData["7"].

The length property does not return the number of items in the array though. It returns the value of the key with the highest numerical value if parsed as a integer plus one.

[messel]

forEach,map, and several other ECMA5 methods look like a joy to use

[msie]

This isn't your father's Array. Sigh.