How to remove/replace first occurrence of character from the right using JavaScript dynamic approach?

Question

example

var string = "ACABBCAA";
var a = "A";
var b = "B";
var c= "C";

output:

removeLastChar(string,a);  //output ACABBCA
removeLastChar(string,b);  //output ACABCAA
removeLastChar(string,c);  //output ACABBAA

What I have tried so far?

Solution 1

 function removeLastChar(string,char){
        result = string.replace(new RegExp('/'+char+'$/'), "");
        return result;
    }

Solution 2

function removeLastChar(string,char){
    result = string.replace('/'+char+'$/', "");
    return result;
}

I already asked in the comments here but not working out.

@Rajesh I have already stored capital letter in a variable. it is not letter, it is variable.. please read full — Sayed Mohd Ali, Aug 06 '19 at 10:21
You should consider using [`lastIndexOf`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/lastIndexOf) — hindmost, Aug 06 '19 at 10:22
@hindmost how can i replace or remove the last occurrence of a character using lastindexof? it will just help me out to search it in string, I already know the character — Sayed Mohd Ali, Aug 06 '19 at 10:23
Begin from [this](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Text_formatting) — hindmost, Aug 06 '19 at 10:26
reverse the string, remove the character and reverse it back. — Rohit Kashyap, Aug 06 '19 at 10:28
I know but since you came up with a better approach already, I was suggesting an alternative. — Rohit Kashyap, Aug 06 '19 at 10:32

iamousseni · Answer 1 · 2019-08-06T10:40:07.253

This is my way to do it

var text = "ACABBCAA";
var a = "A";
var b = "B";
var c= "C";
function removeLastChar(string,char){
  let charLastPosition = string.lastIndexOf(char);
  let newString = string.substring(0, charLastPosition) + string.substring(charLastPosition + 1);
  return newString;
}

document.write(removeLastChar(text, a));

if you wanna replace you can do it un this way.

var text = "Notion,Data,Identity,";
var a = "A";
var b = "B";
var c= "C";
function replaceLastChar(string,char, charToReplace){
    let charLastPosition = string.lastIndexOf(char);
    let newString = string.substring(0, charLastPosition) + charToReplace + string.substring(charLastPosition + 1);
  return newString;
}

document.write(replaceLastChar(text, ',', '.'));

score 1 · Accepted Answer · answered Aug 06 '19 at 10:32

1

Use lastIndexOf and splice with spread notation ....

function removeLastChar(string, char) {
  let strArr = [...string];
  strArr.splice(string.lastIndexOf(char), 1);
  return strArr.join("");
}

answered Aug 06 '19 at 10:32

Jack Bashford

43,180
11
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score 0 · Answer 3 · answered Aug 06 '19 at 10:31

0

You could use a dynamic regex like this: ${char}(?=[^${char}]*$) (For B it would be: B(?=[^B]+$)). This will match the last instace of a character and replace it with empty string

function removeLastChar(str, char) {
  const regex = new RegExp(`${char}(?=[^${char}]*$)`)
  return str.replace(regex, '')
}

console.log(removeLastChar("ACABBCAA", "A"));
console.log(removeLastChar("ACABBCAA", "B"));
console.log(removeLastChar("ACABBCAA", "C"));

answered Aug 06 '19 at 10:31

adiga

34,372
9
61
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Instead of a negated character class, why not a simple negated lookahead? – Jack Bashford Aug 06 '19 at 10:33
@JackBashford how would that look like, for example `A`? – adiga Aug 06 '19 at 10:34

How to remove/replace first occurrence of character from the right using JavaScript dynamic approach?

3 Answers3