Regular expression in javascript with OR condition

Question

I need to create a regular expression that is able to determine //example or //www.example in the website URL . I get the url location of website by ,

var urlOfWeb = location.href ;

I created a regular expression in JavaScript which gives an irregular output when run multiple times . I tried it in firefox browser / console / Phpstorm IDE . Here is the expression ,

// The regular expression
    var expToLookFor = /(\/\/example|\/\/www\.example)/g;
// Using test method of Regexp object of javascript which gives bool result
expToLookFor.test("//example") ;
// Result : true
expToLookFor.test("//example") ;
// Result : false

enter image description here

@siddarth there are many questions here regarding this issue. Please do a search before asking. — Avinash Raj
– Avinash Raj, Commented Apr 6, 2015 at 16:38

anubhava · Accepted Answer · 2015-04-06 16:37:53Z

9

Remove global flag from your regex to make it:

var expToLookFor = /(\/\/example|\/\/www\.example)/;

As g flag makes RegExp object remember it's last position lastIndex.

Better you refactor your regex to:

var expToLookFor = /\/\/(www\.)?example/;

answered Apr 6, 2015 at 16:37

anubhava

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2 Comments

hwnd Over a year ago

Those are some ugly mountains =)

Siddharth Sharma Over a year ago

@Anubhava : It worked very well . I would have selected your answer after a minute of your posting the answer but I had to wait for 15min before I can select an answer , must be some stackoverflow rule . Anyways , Thank you .

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