REGEXP js dot not working

Question

I am trying to use regex to validate a form in js, but I encountered a problem, which I could no google successfully.

When I create any RegExp in js, for example with the /(.)*/ the test function returns false no matter on what I test it... In php and regex online editors it works fine.

I tried to google it, but without any success, it seems as everyone is using the:

var regexp = /expression/

My code:

var reg = new RegExp("/(.)+/", "g");
console.log("Regexp:" + reg.test("a"));

Also I have been told that the regex in php should be compatible with the regex in js...

What does your regex test?

Lixus
– Lixus

2017-05-12 18:20:19 +00:00
Commented May 12, 2017 at 18:20 — Lixus
– Lixus, Commented May 12, 2017 at 18:20

Jordan Soltman · Accepted Answer · 2017-05-12 18:21:09Z

4

Your syntax is incorrect. You either need to remove the quotes, or remove the slashes. See the documentation here.

var reg = new RegExp(/(.)+/, "g");
console.log("Regexp:" + reg.test("a"));

answered May 12, 2017 at 18:21

Jordan Soltman

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2 Comments

Samuel Kodytek Over a year ago

Thank you, it works but is there any big difference between these two solutions? removing the quotes or removing the slashes?

quackenator Over a year ago

It's basically run-time vs evaluation time compilation. Which becomes more apparent in a loop with a large number of iterations.

Nhor · Accepted Answer · 2017-05-12 18:21:00Z

4

When you're using the RegExp object you shouldn't add / signs in the definitions. Simply use var reg = new RegExp("(.)+", "g");

answered May 12, 2017 at 18:21

Nhor

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2 Comments

Samuel Kodytek Over a year ago

Ty, it works, but also stackoverflow.com/a/43944221/5070552 works, is there any big difference?

quackenator Over a year ago

Use literal notation when the regular expression will remain constant The Description section gives a pretty good explanation.

Daniel Dwyer · Accepted Answer · 2017-05-12 18:21:36Z

0

The major difference between JS and PHP Regex is: javascript : /[a-z]+/ php : '/[a-z]+/'

Simply the single quotes on each end of the regex expression.

answered May 12, 2017 at 18:21

Daniel Dwyer

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