Javascript remove Regex Delimiter

Question

My code in PHP generate a JSON based on the user input.

Inside this JSON, I have a Regex string "/regex/gi" with the delimiter.

I send this to the user and I would like javascript to test a string based on that regex. But since I have the delimiter inside the string, it does not work.

Sometime, I can receive the regex string as "regex", "/regex/" or "/regex/gi" So is there a way to remove thoses delimiter, or transform the string in a regex.

I tried to use "new RegExp" but it escape the string, and it won't work.

Here some code:

var json = {regex: "/hello/"}; //This code is generated by PHP
"hello".match(json.regex); //Test in javascript, not working, since the "/" are inside the regex and not used as delimiter

Anyone have an idea how I could do this?

Thank

@balajimca var json = { regex: "/hello/" } //Generated by php, "hello".match(json.regex); //Not working, only work if the string is "/hello/" — Etienne
– Etienne, Commented Jun 25, 2013 at 12:36
bro, Can you update your question with your code. Not in comment section :) — Balaji Kandasamy
– Balaji Kandasamy, Commented Jun 25, 2013 at 12:40
You should accept one format, otherwise you will bump into problems. I'll show you an example: user1 tries /\/\//, user2 tries /\/\//gi and user3 \/\/ (without delimiters). If we removed the / from the begin and the end, the third user will have a problem. — HamZa
– HamZa, Commented Jun 25, 2013 at 12:43

Tom Pietrosanti · Accepted Answer · 2013-06-25 13:16:14Z

2

You could regex your regex (woah)

var reMeta = /(^|[^\\])\/(\w+$){0,1}/;
var json = {regex: "/hello\/slash\//gi"};

json.regex = new RegExp( json.regex.replace(reMeta,'$1') );
// after replace it looks like: "hello\/slash\/"

edited Jun 25, 2013 at 13:16

answered Jun 25, 2013 at 13:04

Tom Pietrosanti

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Stanislav Terletskyi · Accepted Answer · 2013-06-25 12:55:18Z

1

var json = {regex: "/hello/"};

"hello".match(eval(json.regex));//Simle way (bad practice, but will work)

More propel way:

var json = {regex: "hello"};
var reg = new RegExp(json.regex)
var matched = reg.exec("hello") != null;

edited Jun 25, 2013 at 12:55

answered Jun 25, 2013 at 12:47

Stanislav Terletskyi

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1 Comment

Etienne Over a year ago

I would highly prefer not to use eval. I tried the new RegExp class, but if the input is "/hello/" RegExp will escape the "/", I need a way to simply remove them.

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