Question

So I have this string, that represents a math expression:

(timezone*timelapse)-time

Each word represents an id from an input field, and currently i was merely replacing each word with a prototype js expression to be evaled later:

$('timezone').value,

$('timelapse').value

The problem is the last id. By the time i reach it, my expression is currently like this:

($('timezone').value*$('timelapse').value)-time

So when I search for the word time to replace it with $('time').value it will affect the first two values and messing the final expression.

My question here is: How can I replace the correct word here?

Since this a math expression the word should probably be between any math symbols like this:

(+-/* **word** +-/*)

[empty space] **word** +-/*)

(*-/* **word** [empty space]

Or not?

Answer 1

Try this:

var newString = oldString.replace(/\btime\b/, "$('time').value")

\b is a word boundary, meaning the regex only matches time if it’s a stand-alone word, not when it’s directly followed or preceded by any word characters.