Name
String.substr( ) — extract a substring
Availability
JavaScript 1.2; JScript 3.0; deprecated
Synopsis
string.substr(start,length)
Arguments
-
start The start position of the substring. If this argument is negative, it specifies a position measured from the end of the string: -1 specifies the last character, -2 specifies the second-to-last character, and so on.
-
length The number of characters in the substring. If this argument is omitted, the returned substring includes all characters from the starting position to the end of the string.
Returns
A copy of the portion of string starting
at and including the character specified by
start and continuing for
length characters, or to the end of the
string if length is not specified.
Description
substr( ) extracts and returns a substring of
string. It does not modify
string.
Note that substr( ) specifies the desired
substring with a character position and a length. This provides a
useful alternative to String.substring( ) and
String.splice( ), which specify a substring with
two character positions. Note, however, that this method has not been
standardized by ECMAScript and is therefore deprecated.
Example
var s = "abcdefg"; s.substr(2,2); // Returns "cd" s.substr(3); // Returns "defg" s.substr(-3,2); // Should return "ef"; returns "ab" in IE 4
Bugs
Negative values for start do not work in
JScript 3.0 (IE 4). Instead of specifying a character position
measured from the end of the string, they specify character position
0.