Copying an Array (Referenced & Non-Referenced/Snapshot)

Copying_Arrays.js

// generally for in loops are used to save a non-referenced copy/snapshot of an array. this is a far simpler method to acheive the same

var arr = [1, 2, 3];

// referenced copy of an array.
var arr_ref_copy = arr;

// non-referenced copy or snapshot of an array.
var arr_snapshot = arr.slice(0);

// update original array.
arr.push(4);

console.log(arr_ref_copy); // returns [1, 2, 3, 4] - referenced copy gets updated.
console.log(arr_snapshot); // returns [1, 2, 3] - non-referenced copy/snapshot is unchanged.

/**
 * Note:
 * If its an array like object like "arguments" of a function use -
 * var arguments_snapshot = Array.prototype.slice.call(arguments, 0);
 */