Pass a variable into regex with string replace

Question

I have a complicated regEx inside a string replace and I want to use a variable called "tagname" instead of the word Category, but I don't know how to do this.

$("textarea").val().replace(/\<Category\>(.*)\<\/Category\>/gi, "<Category>TextVariable</Category>");

I have tried something like this, but it didn't work in the first parameter.

$("textarea").val().replace("/\<" + tagname + "\>(.*)\<\/" + tagname "\>/gi", "<" + tagname + ">" + TextVariable + "</" + tagname + ">");

Tim Down · Accepted Answer · 2010-06-29 09:59:41Z

6

You can use the RegExp constructor with a string pattern and flags:

var regex = new RegExp("<" + tagname + ">(.*)</" + tagname + ">", "gi");
$("textarea").val().replace(regex, "<" + tagname + ">" + TextVariable + "</" + tagname + ">");

answered Jun 29, 2010 at 9:59

Tim Down

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Community · Accepted Answer · 2017-05-23 12:34:19Z

6

Use the RegExp constructor instead of regex literal.

var regex = new RegExp("<" + tagname + ">(.*)</" + tagname + ">", "gi");
$("textarea").val().replace(regex, "<" + tagname + ">" + 
   textVariable + "</" + tagname + ">");

you can simplify it as:

//capture the tag name:
var regex = new RegExp("<(" + tagname + ")>(.*)</" + tagname + ">", "gi");
$("textarea").val().replace(regex, "<$1>" + textVariable + "</$1>");

But bear in mind that parsing xml/html with regex is a baaad idea

edited May 23, 2017 at 12:34

CommunityBot

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answered Jun 29, 2010 at 10:00

Amarghosh

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