startsWith method not supported in IE any replacement for this?

Question

var s = "Main String";
s.startsWith("Main");

Replacing startWith with a similar logic or any other method generic to all browsers.

The [docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith) contains a polyfill. — Teemu, Aug 04 '16 at 16:52
Normally, you should’ve Googled _before_ asking a question here. — Sebastian Simon, Aug 04 '16 at 16:52

score 16 · Answer 1 · answered Aug 04 '16 at 17:00

16

A good replacement for startsWith would be using s.substring(0, 4) == 'Main'

This should work, so go ahead and try it.

answered Aug 04 '16 at 17:00

Addisonep

score 4 · Answer 2 · answered Aug 04 '16 at 16:56

4

Add a prototype method in String:

String.prototype.myStartsWith = function(str){
 if(this.indexOf(str)===0){
  return true;
 }else{
   return  false;
 }
};

Now call:

s.myStartsWith("Main");

answered Aug 04 '16 at 16:56

Tuhin

Is the reason against doing this that it's not as efficient as the other solution? – Marcus Mar 19 '18 at 19:34
Remenber to check if exist before overwrite: `if (!String.prototype.startsWith) { String.prototype.startsWith = function(searchString, position){ return this.substr(position || 0, searchString.length) === searchString; }; }` – Juanmabs22 Jan 29 '21 at 13:51

2 Answers2