How to use string with regex metacharacters as regex in replaceText?

Question

I have a bit of code that is searching a document for a tag and replacing it with a specific merge field. This code works fine until my tag has a | (pipe symbol) in it.

For some reason that makes the search only partially match. I suspect this has something to do with it thinking the variable I am passing is a regEx pattern and not a literal string, but I am unsure how to force it to be treated as a string. I use replaceText, which accepts regex as a string.

bodyObject.replaceText(Regex<String>, Replacement<String>);

I use it like this:

bodyObject.replaceText(markup, dataRow[headerIndex]);

In the above example markup that equals "{{ tag | directive }}" would cause the partially match.

Answer 1

If we are expecting the markup to be plain text, you can just escape the whole variable when it is passed as a parameter in replaceText. I don't find this breaking anything you have and you won't modify anything else aside from the replaceText line.

Sample:

function escapeString() {
  var bodyObject = DocumentApp.getActiveDocument().getBody();
  
  markup = "{{ tag | directive }}";
  
  newString = "<mergeField>";
  // escape any non word character ($& = whole matched string)
  bodyObject.replaceText(markup.replace(/\W/g, "\\$&"), newString);
}

Before:

After:

Reference:

• Javascript RegEx
• \\
• $&