buillding regex expression

Question

i want to replace specific amount of white-spaces from a String at the beginning and i can use

replace(/^\s{2}/g,"");

and it works .but 2 should be changed according to a value of a variable .so i need to construct a new RegExp()

so i used

var lead=2;
var regex = new RegExp("\^\\s{" + lead + "}//g");
alert("regex  "+regex);

real output

 /^\s{2}\/\/g/

expected output

/^\s{2}/g

could you help me to fix this problem.tnx

@nhahtdh I don't think this question is duplicate of http://stackoverflow.com/questions/494035/how-do-you-pass-a-variable-to-a-regular-expression-javascript Even the answers on this question will not help to solve this problem — Tushar, Jul 10 '15 at 06:19
@Tushar: Better dup: http://stackoverflow.com/questions/516917/javascript-regexp-objects — nhahtdh, Jul 10 '15 at 06:39

Tushar · Accepted Answer · 2015-07-10T07:12:11.577

2

As the param to RegExp is the regex, you don't need the / delimiters. Use the flags as the second parameter to the RegEx() constructor.

var regex = new RegExp("^\\s{" + lead + "}", 'g');

Example:

var lead = 2;
var regex = new RegExp("^\\s{" + lead + "}", 'gmi');

alert(regex);

var str = '  Say My Name';
alert(str.replace(regex, ''));

edited Jul 10 '15 at 07:12

answered Jul 10 '15 at 06:17

Tushar

one more problem .can i pass 2 flags ?i tried `new RegExp("^\\s{" + lead + "}", 'g','m');` but shows only one flag – Madhawa Priyashantha Jul 10 '15 at 07:11

score 1 · Answer 2 · answered Jul 10 '15 at 06:38

1

new RegExp("^\\s{" + lead + "}", "g");

answered Jul 10 '15 at 06:38

Diode

score -1 · Answer 3 · answered Jul 10 '15 at 06:16

-1

Try

"\^\\s{" + lead + "}\/g"

instead of

"\^\\s{" + lead + "}//g"

I think you wanted to escape the "/", but you accidently used "/" instead of "\".

answered Jul 10 '15 at 06:16

red13

tnx for ur responce but this gives me `/^\s{2}\/g/` – Madhawa Priyashantha Jul 10 '15 at 06:21

3 Answers3