Javascript String Contains Example

In JavaScript String Contains article, I have covered how to check a JavaScript string contains another string.JavaScript is not having contains() method. Mozilla supports contains() method 19.0+ onwards. But other browsers don’t support this method.

We can use String.indexOf() or String.search() functions to implement contains() function.
String.indexOf() –  returns the position of a substring, returns -1 if not found.
String.search() – returns the position of a substring using regular expression, returns -1 if not found.

Below are the different string contains examples and their performance.

//1.Using indexOf, greater than -1
function contains(r,s){
    return r.indexOf(s) > -1;
}

//2.Using indexOf,  not equal to -1
function contains(r,s){
    return r.indexOf(s) !== -1;
}

//3.Using indexOf, bool not with bitwise not
function contains(r,s){
return !!~r.indexOf( s );
}

//4.Using search(), greater than -1
function contains(r,s){
    return r.search(s) > -1;
}

//5.Using search(), not equal to -1
function contains(r,s){
    return r.search(s) !== -1;
}

//6.Using search(), bool not with bitwise not
function contains(r,s){
return !!~r.search( s );
}

Using jsperf.com, we can find the performance of each function. After some trails, Below is the fastest JavaScript string contains function.

You can also perform tests here: http://jsperf.com/hg-string-contains

Function Prototype:

if(!String.prototype.contains)   
{    
  String.prototype.contains = function (str)   
  {    
      return (this.indexOf(str) !== -1);    
  };    
}

How to use it:

var str ='javascript string contains performance. which one is best';
if(str.contains('best'))
{
	alert("String found");
}
else
{
	alert("String not found");
}

References:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/search
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/indexOf