Sorting Javascript Arrays
Use the sort function to sort arrays:
var animals = ["giraffe", "fish", "toad", "aardvark"];
animals.sort();
// animals is now ["aardvark", "fish", "giraffe", "toad"]
Numerical sort requires a comparator function. You cannot use normal sort because “10” will come before “9”. This is the case even if you specified numbers.
var numbers = [20, 10, 30, 9];
numbers.sort();
// numbers is now [10, 20, 30, 9]
Instead, use a comparator function to help sort the array. This function should return a negative, zero, or positive number.
var numbers = [20, 10, 30, 9];
numbers.sort(function(a,b) {
return a - b;
});
// numbers is now [9, 10, 20, 30]
Arrays and Nulls
Below is an example about nulls and arrays
var arrayTest = new Array();
arrayTest[0] = 'hello';
arrayTest[3] = 'bye';
var output = "arrayTest length: " + arrayTest.length;
output += "\n";
output += "0: " + arrayTest[0];
output += "\n";
output += "1: " + arrayTest[1];
output += "\n";
if (arrayTest[1] == null) {
output += "arrayTest[1] is null\n";
}
output += "2: " + arrayTest[2];
output += "\n";
output += "3: " + arrayTest[3];
output += "\n";
output now holds:
arrayTest length: 4
0: hello
1: undefined
arrayTest[1] is null
2: undefined
3: bye