Why String.indexOf check failed in JavaScript?

Question

From this famous high-voted question I've find an effective way to check if a string contains another string or not with String.indexOf.

var abcde = "abcdefg";
var abc = "abc";
alert(abc.indexOf(abcde) != -1);//return true

But when I try to do like this:

var url = "https://stackoverflow.com/questions/1789945/method-like-string-contains-in-javascript";
var s = "stackoverflow";
alert(s.indexOf(url) != -1); //**return false,but I think it 'should' return true!**

I'm curious that why a more complex which contains symbol or slash / seems to be failed. Or did I miss something?

Denys Séguret · Accepted Answer · 2013-08-07 09:23:16Z

5

The string you search is the parameter, not the receiver.

Change

alert(s.indexOf(url) != -1);

to

alert(url.indexOf(s) != -1);

(and you should also use console.log instead of alert, for your own comfort)

answered Aug 7, 2013 at 9:23

Denys Séguret

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