帮助用正则表达式替换文本

Question

I have the following text in a file called build.xml:

component.rollup=true
component.rollup.modules.buildfiles=io-base.xml, io-form.xml, io-xdr.xml
component.rollup_dir=/base

I want it to add one file in it so it will become:

component.rollup=true
component.rollup.modules.buildfiles=io-base.xml, io-form.xml, io-xdr.xml, io-extended.xml
component.rollup_dir=/base

How can I do that with regex?

I'm using javascript.

Thanks!

EDIT:

Forgot to tell you that the files are not static, they may change. Only

component.rollup.modules.buildfiles=

will always be there.

Answer 1

Assuming you have already read the contents of the file:

fileContents.replace(
  /^(component\.rollup\.modules\.buildfiles\s*=.*)$/m,
  '$1, io-extended.xml');

Answer 2

Try this (assuming the variable with the XML contents in it is called myXmlContent ):

if (!myXmlContent.match(/^component\.rollup\.modules\.buildfiles=.*io-extended\.xml/im) {
    myXmlContent = myXmlContent.replace(/^(component\.rollup\.modules\.buildfiles=.*)$/im, '$1, io-extended.xml');

This will ensure it isn't added twice.