Function that returns the opposite letter

Question

I want to write a function that returns alternating characters, so for instance:

"hello world".toAlternatingCase() === "HELLO WORLD"
"HELLO WORLD".toAlternatingCase() === "hello world"
"HeLLo WoRLD".toAlternatingCase() === "hEllO wOrld"

Here is my try

const alternatingCase = function (string) {
  let newword = "";

  for (i = 0; i<string.length; i++) {
     if (string.charAt(i).toUpperCase())
    {
    newword+= string.charAt(i).toLowerCase()
    }

   else 
   {
   newword+=string.charAt(i).toUpperCase()
   }
  }
  return newword  
}

When invoked, the function unfortunately only returns the string itself, not sure what I'm doing wrong though, thanks very much for reading or even helping out!

Hey check this post https://stackoverflow.com/questions/8392035/add-method-to-string-class — Vadym, Jun 08 '20 at 07:35

Nina Scholz · Answer 1 · 2020-06-08T07:32:39.650

You need to check if the caracter is uppercase and take then lower case.

Don't forget to declare all variables.

This approach uses a conditional (ternary) operator ?: where a condition is used to return two different expressions.

const alternatingCase = function(string) {
    let newword = "";

    for (let i = 0; i < string.length; i++) {
        let character = string[i];
        newword += character === character.toUpperCase()
            ? character.toLowerCase()
            : character.toUpperCase();
    }
    return newword;
}

console.log(alternatingCase('Test'));

If you really need to use the function as prototype of string, you need to assign the function to String.prototypeand the wanted method. For this you need to address this, to get the value of the string.

String.prototype.alternatingCase = function() {
    let newword = "";

    for (let i = 0; i < this.length; i++) {
        let character = this[i];
        newword += character === character.toUpperCase()
            ? character.toLowerCase()
            : character.toUpperCase();
    }
    return newword;
}

console.log('Test'.alternatingCase());

score 0 · Accepted Answer · answered Jun 08 '20 at 07:32

you've done the compression wrong

checkout this

function alternatingCase(string) {
  let newword = "";

  for (i = 0; i < string.length; i++) {
     const c = string.charAt(i);
     if (c === c.toUpperCase()){
        newword += c.toLowerCase()
     } else {
       newword += c.toUpperCase()
     }
  }
  
  return newword;
}

console.log(alternatingCase("TesT"));

score 0 · Answer 3 · answered Jun 08 '20 at 07:34

All you need to update is your condition to if (string.charAt(i) === string.charAt(i).toUpperCase()). You have to compare your uppercase letter to original letter.

const alternatingCase = function(string) {
  let newword = "";

  for (i = 0; i < string.length; i++) {
    if (string.charAt(i) === string.charAt(i).toUpperCase()) {
      newword += string.charAt(i).toLowerCase()
    } else {
      newword += string.charAt(i).toUpperCase()
    }
  }
  return newword
}

console.log(alternatingCase("HeLLo WoRLD"));

Function that returns the opposite letter

3 Answers3