Javascript Regex Object and Dollar Symbol

Question

In the code below. I expected to be back, but instead I get a lie. What am I missing?

var text = "Sentence $confirmationlink$ fooo"; alert(placeHolderExists(text,'confirmationlink'); // alerts false function placeHolderExists(text,placeholdername) { var pattern = new RegExp('\$'+placeholdername+'\$'); return pattern.test(text); } 

Answer 1

"\" in the RegExp expression builder is treated as an escape character when constructing a string, just like in a real RegExp. You need to escape twice, try:

 new RegExp('\\$'+placeholdername+'\\$'); 

Answer 2

Must be

 function placeHolderExists(text,placeholdername) { var pattern = new RegExp('\\$'+placeholdername+'\\$'); return pattern.test(text); } 

You need to double access your $ signs

EDIT:
annakata explains why.

Answer 3

This confusion is another example of why you shouldn't use regex if you really don't need to.

 return text.indexOf('$'+placeholdername+'$')!=-1; 

... simpler, faster and does not fall when it has funny characters.

Answer 4

Double slash.

 new RegExp('\\$'+placeholdername+'\\$');