I know that str.replace(/x/g, "y")replaces all x's in the string but I want to do this
function name(str,replaceWhat,replaceTo){ str.replace(/replaceWhat/g,replaceTo); } How can i use a variable in the first argument?
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2 Answers
The RegExp constructor takes a string and creates a regular expression out of it.
function name(str,replaceWhat,replaceTo){ var re = new RegExp(replaceWhat, 'g'); return str.replace(re,replaceTo); } If replaceWhat might contain characters that are special in regular expressions, you can do:
function name(str,replaceWhat,replaceTo){ replaceWhat = replaceWhat.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&'); var re = new RegExp(replaceWhat, 'g'); return str.replace(re,replaceTo); } 
9 Comments
pts
This doesn't work as expected if replaceWhat contains regexp metacharacters, e.g.
*, +, [.
Barmar
@pts So does a literal regexp.
dc5
Then add this logic in as well: Is there a RegExp.escape function in Javascript?
dronus
If used like the asker intended, this will give wrong results if metacharacters appear in replaceWhat. So better chose another answer!
Barmar
@thatOneGuy Good catch, I've added a
return to the functions. I was obviously focused on the regexp part, not the replace part. |
The third parameter of flags below was removed from browsers a few years ago and this answer is no longer needed -- now replace works global without flags
Replace has an alternate form that takes 3 parameters and accepts a string:
function name(str,replaceWhat,replaceTo){ str.replace(replaceWhat,replaceTo,"g"); } https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace
4 Comments
pts
This is Firefox-specific, in Chrome it replaces only the first occurrence.
Hogan
True... it had the "nonstandard" flag.
thatOneGuy
remember, you need to bind this to a new variable : stackoverflow.com/questions/12231644/…
Freddy Daniel
@Hogan this is not working currently please remove this answer or update with working solution.