Javascript tricks for traversing arrays

Array_taversing.js

// toggle between two list values
var i = 1,
    toggleList = ['one', 'two'];

console.log(toggleList[i ^= 1]); // one
console.log(toggleList[i ^= 1]); // two
console.log(toggleList[i ^= 1]); // one

// toggle through longer array
// limitation: list values should not be falsy ("", null, 0)
var j = -1,
    list = ['one', 'two', 'three'];

console.log(list[j = (list[++j]) ? j : 0]); // one
console.log(list[j = (list[++j]) ? j : 0]); // two
console.log(list[j = (list[++j]) ? j : 0]);// three
console.log(list[j = (list[++j]) ? j : 0]); // one

// iterate through array once
// limitation: list values should not be falsy ("", null, 0)
// works cause ++ is executed after returning the variable 
var k = 0,
    list = ['one', 'two', 'three'],
    val;
    
while (val = list[k++]) {
  console.log(val); // one, two, three
}

// reverse iterate through array
var list = ['one', 'two', 'three'],
    i = list.length;
    
while (i--) {
  console.log(list[i]); // three, two, one
}

// init array with zeros
// array map needs polyfill for ie8 (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map)
var arr = Array.apply(null, new Array(10)).map(function () {return 0;});
console.log(arr); //[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]