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

Availability

JavaScript 1.1; JScript 3.0; ECMAScript v1; enhanced in
ECMAScript v3

Synopsis

string.split(delimiter, limit)

Arguments

delimiter

The string or regular expression at which the
string splits. The use of a regular
expression as a delimiter is standardized by ECMAScript v3 and
implemented in JavaScript 1.2 and JScript 3.0; it is not implemented
in JavaScript 1.1.

limit

This optional integer specifies the maximum length of the returned
array. If specified, no more than this number of substrings will be
returned. If not specified, the entire string will be split,
regardless of its length. This argument is standardized by ECMAScript
v3 and implemented in JavaScript 1.2 and JScript 3.0; it is not
implemented in JavaScript 1.1.

Returns

An array of strings, created by splitting
string into substrings at the boundaries
specified by delimiter. The substrings in
the returned array do not include
delimiter itself, except in the case noted
below.

Description

The split( ) method creates and returns an array
of as many as limit substrings of the
specified string. These substrings are created by searching the
string from start to end for text that matches
delimiter and breaking the string before
and after that matching text. The delimiting text is not included in
any of the returned substrings, except as noted below. Note that if
the delimiter matches the beginning of the string, the first element
of the returned array will be an empty string -- the text that
appears before the delimiter. Similarly, if the delimiter matches the
end of the string, the last element of the array (assuming no
conflicting limit) will be the empty
string.

If no delimiter is specified, the string
is not split at all, and the returned array contains only a single,
unbroken string element. If delimiter is
the empty string or a regular expression that matches the empty
string, the string is broken between each character, and the returned
array has the same length as the string does, assuming no smaller
limit is specified. (Note that this is a
special case since the empty string before the first character and
after the last character is not matched.)

We said above that the substrings in the array returned by this
method do not contain the delimiting text used to split the string.
However, if delimiter is a regular
expression that contains parenthesized subexpressions, the substrings
that match those parenthesized subexpressions (but not the text that
matches the regular expression as a whole) are included in the
returned array.

Note that the String.split( ) method is the
inverse of the Array.join( ) method.

Example

The split( ) method is most useful when you are
working with highly structured strings. For example:

"1:2:3:4:5".split(":");  // Returns ["1","2","3","4","5"]
"|a|b|c|".split("|");    // Returns [", "a", "b", "c", "] 

Another common use of the split( ) method is to
parse commands and similar strings by breaking them down into words
delimited by spaces:

var words = sentence.split(' '); 

See the Section section for details on a special case when
delimiter is a single space. It is easier
to split a string into words using a regular expression as a
delimiter:

var words = sentence.split(/\s+/); 

To split a string into an array of characters, use the empty string
as the delimiter. Use the limit argument
if you only want to split a prefix of the string into an array of
characters:

"hello".split(");     // Returns ["h","e","l","l","o"]
"hello".split(", 3);  // Returns ["h","e","l"] 

If you want the delimiters, or one or more portions of the delimiter
included in the returned array, use a regular expression with
parenthesized subexpressions. For example, the following code breaks
a string at HTML tags and includes those tags in the returned array:

var text = "hello <b>world</b>";
text.split(/(<[^>]*>)/);  // Returns ["hello ","<b>","world","</b>","] 

Bugs

In Netscape's implementations of JavaScript, when language
Version 1.2 is explicitly requested (with the
language attribute of a
<script> tag, for example), the
split( ) method has one special-case behavior: if
delimiter is a single space, the method
splits the string at spaces but ignores any white space at the
beginning and end of the string. See Section 11.6, for further details.

See Also

Array.join( ), RegExp; Chapter 10