javascript - Better Way to Escape Dollar Signs in the String Used By String.prototype.replace

Question

I want to replace a string by another. I found when the replaceValue contains "$", the replace will fail. So I am trying to escape "$" by "$$" first. The code is looks like this:

var str = ..., reg = ...;
function replaceString(replaceValue) {
  str.replace(reg, replaceValue.replace(/\$/g, '$$$$'));
}

But I think it is ugly since I need to write 4 dollar signs.

Is there any other charactors that I need to escape? And is there any better way to do this?

Answer 1

There is a way to call replace that allows us not to worry about escaping anything.

var str = ..., reg = ...;
function replaceString(replaceValue) {
  return str.replace(reg, function () { return replaceValue });
}

Answer 2

Your method to escape the replacement string is correct.

According to section 15.5.4.11 String.prototype.replace of ECMAScript specification edition 5.1, all special replacement sequences begins with $ ($&, $`, $', $n, $nn) and $$ specify a single $ in the replacement.

Therefore, it is sufficient to escape all $ with double $$ like what you are doing right now if the replacement text is meant to be treated literally.

There is no other concise way to do the replacement as far as I can see.

Answer 3

Unfortunately, nothing you can do about it.
It's just how JavaScript works with regular expressions.

Here's a good article with the list of all replacement patterns you should be aware of: http://es5.github.io/#x15.5.4.11