Name
String.lastIndexOf( ) — search a string backward
Availability
JavaScript 1.0; JScript 1.0, ECMAScript v1
Synopsis
string.lastIndexOf(substring)string.lastIndexOf(substring,start)
Arguments
-
substring The substring that is to be searched for within
string.-
start An optional integer argument that specifies the position within
stringwhere the search is to start. Legal values are from 0 (the position of the first character in the string) tostring.length-1 (the position of the last character in the string). If this argument is omitted, the search begins with the last character of the string.
Returns
The position of the last occurrence of
substring within
string that appears before the
start position, if any, or -1 if no
such occurrence is found within string.
Description
String.lastIndexOf( ) searches the string from end
to beginning to see if it contains an occurrence of
substring. The search begins at position
start within
string, or at the end of
string if start
is not specified. If an occurrence of
substring is found,
String.lastIndexOf( ) returns the position of the
first character of that occurrence. Since this method searches from
end to beginning of the string, the first occurrence found is the
last one in the string that occurs before the
start position.
If no occurrence of substring is found,
String.lastIndexOf( ) returns -1.
Note that although String.lastIndexOf( ) searches
string from end to beginning, it still
numbers character positions within string from the beginning. ...