Javascript Algorithms and Data Structures Challenge: Day 8

Direction: How to remove the last char appeared in a sentence.

Example: Remove last “n” from “How to remove the last empty space in a sentence.” beomes “How to remove the last empty space in a sentece.”

Solution 1:

1. Convert into array of chars
2. Reverse
3. Remove 1st
4. Convert back

let s="Hello, wold";
String.prototype.reverse= function () {
  return this.split('').reverse().join('');
  
}
String.prototype.removeFirst=function (c){
  return this.replace(c,'');
}
s=s.reverse();
s=s.removeFirst('l');
s=s.reverse();
console.log(s)
//"Hello, wod"

Solution 2:

1. Convert to array
2. Remove
3. Rejoin

let s="Hello, wolld";
function removeLast(str, c){
  const arr=s.split(c);
  
  const newString=arr.reduce((a, v, i, r)=>{
   if( i === (r.length-1)){
      return a+v;
    }
       
    if( i === (r.length-2)){
      return a+v;
    }
       
    return a+v+c;
  
  },'')
 return newString;
}
console.log(removeLast(s, 'l'));

Solution3:

1. splice method
2. join

let s="Hello, wolld";
function removeLast(str, c){
  let arr=s.split('');
  let lastIndex, newArr, newStr;
  
  for(let i=0; i<arr.length;i++){
    let tmp=arr[i];
    if(tmp===c){
      lastIndex=i;
    } 
    
  }
  
      
  if(lastIndex){
    arr.splice(lastIndex, 1);
    newStr=arr.join('');
  }
return newStr;
}
console.log(removeLast(s, 'l'))