Javascript [Electronic resources] : The Definitive Guide (4th Edition) نسخه متنی

Availability

JavaScript 1.1; JScript 2.0; ECMAScript v1

Synopsis

array.sort( ) array.sort(orderfunc)

Arguments

orderfunc

An optional function used to specify the sorting order.

Returns

A reference to the array. Note that the array is sorted in place and
no copy is made.

Description

The sort( ) method sorts the elements of
array in place -- no copy of the array
is made. If sort( ) is called with no arguments,
the elements of the array are arranged in alphabetical order (more
precisely, the order determined by the character encoding). To do
this, elements are first converted to strings, if necessary, so that
they can be compared.

If you want to sort the array elements in some other order, you must
supply a comparison function that compares two values and returns a
number indicating their relative order. The comparison function
should take two arguments, a and
b, and should return one of the following:

• A value less than zero, if, according to your sort criteria,
  a is "less than"
  b and should appear before
  b in the sorted array.
  




• Zero, if a and
  b are equivalent for the purposes of this
  sort.
  




• A value greater than zero, if a is
  "greater than" b for the
  purposes of the sort.
  

Note that undefined elements of an array are always sorted to the end
of the array. This is true even if you provide a custom ordering
function: undefined values are never passed to the
orderfunc you supply.

Example

The following code shows how you might write a comparison function to
sort an array of numbers in numerical, rather than alphabetical
order:

// An ordering function for a numerical sort
function numberorder(a, b) { return a - b; }
a = new Array(33, 4, 1111, 222);
a.sort(  );             // Alphabetical sort: 1111, 222, 33, 4
a.sort(numberorder);    // Numerical sort: 4, 33, 222, 1111