javascript regular expressions with variable content

Question

I have a working reg expression that does a replace function based on the expression. It works perfect. It finds a specific string based on the beginning of the string and the expression. This is it:

str.replace(/\bevent[0-9]*\=/, "event");

what this does is it changes event=1 to event.

What if event was a variable word? What if I needed to look for conference also?

I have tried:

var type = "conference";

str.replace(/\b/ + type+ /[0-9]*\=/, "conference");

and:

str.replace(/\b/type/[0-9]*\=/, "conference");

neither worked.

how can I pass a javascript string into a regular expression?

deceze · Accepted Answer · 2011-03-05 06:50:24Z

2

Instead of writing a RegEx literal, use a string to create a new RegExp object:

str.replace(new RegExp('\b' + var + '[0-9]'), …)

answered Mar 5, 2011 at 6:50

deceze♦

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1 Comment

mtlca401 Over a year ago

I guess its kind of messed up that I can only pick one answer, but your answer worked perfectly. I did have to take out the '\b' though. That didn't work for some reason.

Shad · Accepted Answer · 2011-03-05 06:50:29Z

1

You can do that with the RegExp Object:

str.replace(RegExp('\b' + reStr + '[0-9]*\='),StrToReplaceWith)

answered Mar 5, 2011 at 6:50

Shad

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2 Comments

mtlca401 Over a year ago

I took your answer because it fit exactly what I was looking for. Is it strange that the '\b' would not work? I had to take it out.

Shad Over a year ago

I'm afraid I don't have much experience with the word boundary character =(

Kyle · Accepted Answer · 2011-03-05 06:53:19Z

0

Create a new regex object with your variable.

read this...

http://www.w3schools.com/js/js_obj_regexp.asp

answered Mar 5, 2011 at 6:53

Kyle

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1 Comment

Kyle Over a year ago

Ok. This still answers his question.

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