如何使用 JavaScript 动态方法从右侧删除/替换第一次出现的字符？

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.

Answer 1

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, ',', '.'));

Answer 2

Use lastIndexOf and splice with spread notation ... .

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

Answer 3

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"));