I want to remove only one character before particular symbol for example:

Question

I want to remove a specific character, as well as the one before it (in this case # and its preceding character). Example:

"ab#c" -> "ac"

Answer 1

Use a regex and String.replace :

 const inp = "ab#c"; const match = /.#/; const out = inp.replace(match, ""); console.log(out);

Note that this removes any character preceding a '#' in your original string, but only a single occurrence. Add the g flag to match and replace all occurrences, and use [a-zA-Z] to just match letters.

If you want to work the other way (character following, not preceding), and want to replace #c but not \#c , just add that as well:

 const inp = "ab\\#c3#cc"; const match = /[^\\]{1}#./; const out = inp.replace(match, ""); console.log(out);

Answer 2

You can use global regex replace

 const inputStr = "ab#c de#f gh#i"; const regxStr = /.#/g; const outputStr = inputStr.replace(regxStr, ""); console.log(outputStr);