javascript determines whether a string contains a certain string and indexOf usage examples

javascript determines whether a string contains a certain string and indexOf usage examples_javascript skills

WBOY

Release： 2016-05-16 17:19:33

Original

916 people have browsed it

Realize the display of advertisements by judging the specified directory

Copy the code The code is as follows:

 
if (location.href.indexOf("http://www.jb51.net/codes/")>-1){ 
alert('ok'); 
} 

Copy code The code is as follows:

 
var Cts = "bblText"; 
if (Cts.indexOf("Text") >= 0 ) 
{ 
alert('Cts contains Text string'); 
} 

indexOf Usage:

Returns the character position of the first substring occurrence in the String object.

strObj.indexOf(subString[, startIndex])

Parameters

strObj

Required. String object or literal.

subString

Required. The substring to find in the String object.

starIndex

Optional. This integer value indicates the index within the String object at which to begin the search. If omitted, the search is from the beginning of the string.

Description

The indexOf method returns an integer value indicating the starting position of the substring within the String object. If the substring is not found, -1 is returned.

If startindex is negative, startindex is treated as zero. If it is greater than the largest character position index, it is treated as the largest possible index.

Perform the search from left to right. Otherwise, the method is the same as lastIndexOf.

Example

The following example illustrates the usage of the indexOf method.

Copy code The code is as follows:

 
function IndexDemo(str2){ 
var str1 = "BABEBIBOBUBABEBIBOBU" 
var s = str1.indexOf(str2); 
return(s); 
} 

For JavaScript indexOf ignore case

The indexOf function method in JavaScript returns an integer value indicating the starting position of the substring within the String object. If the substring is not found, -1 is returned. If startindex is negative, startindex is treated as zero. If it is greater than the largest character position index, it is treated as the largest possible index.
The indexOf function performs searches from left to right. Otherwise, the method is the same as lastIndexOf.

The following example illustrates the usage of the indexOf function method

Copy code The code is as follows :

 
function IndexDemo(str2){ 
var str1 = "BABEBIBOBUBABEBIBOBU" 
var s = str1.indexOf(str2); 
return(s); 
} 