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I want to match the URL host part with a regular express in JavaScript. Suppose I have a URL 

var str = 'www.demo-site.com:1234'

and I designed below regular expression to match it

var regex = /^www\.demo-site\.com(:\d+)$/gi

As I expected, regex.test(str) returns true. However, if I run it again, it returns false. Why the results from running exactly the same function twice are different?

regex.test(str); //returns true
regex.test(str); //returns false

Shuping
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1 Answers1

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That's because the search starts from the previous match for each invocation of test:

test called multiple times on the same global regular expression instance will advance past the previous match.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/test

twaddington
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