Several implementation methods of startWith and endWith in javascript_javascript skills

JavaScript uses regular expressions to implement startWith and endWith effect functions

Copy code The code is as follows:

String.prototype.startWith=function(str){ 
var reg=new RegExp("^" str); 
return reg.test(this); 
}

String .prototype.endWith=function(str){ 
var reg=new RegExp(str "$"); 
return reg.test(this); 
}

JavaScript Implement startWith and endWith effect functions

Copy code The code is as follows:

//The following is an example of usage
var url = location.href;
if (url.startWith('http:// www.jb51.net'))
{
//If the current url starts with http://www.jb51.net/
}

Another one is It is implemented using indexOf:

Copy the code The code is as follows:

var index = str.indexOf( 'abc');

if(index==0){

//Start with 'abc'

}