Anticipated a false result when comparing an empty string in JavaScript

Question

Anticipated a false result when comparing an empty string in JavaScript

Struggling with the CodeWars challenge The Hashtag Generator :

The marketing team needs help creating hashtags fast.
Let's simplify things with our own Hashtag Generator!

Here's what we need:

It should begin with a hashtag (#).

All words should be capitalized.

If the final result exceeds 140 characters, return false.

If either the input or output is empty, return false.

Examples
" Hello there thanks for trying my Kata"  =>  "#HelloThereThanksForTryingMyKata"
"    Hello     World   "                  =>  "#HelloWorld"
""                                        =>  false

This is my solution:

function generateHashtag (str) {
   if (str == "") {return false;}
   else
     {
      let text = str.trim();
      const myArray = text.split(" ");
      let word ="";
      let finalResult = ""
      for(let i=0; i< myArray.length; i++)
        {
          word = myArray[i];
          word = word.charAt(0).toUpperCase() + word.slice(1);
          finalResult =finalResult + word;
        }
      if(finalResult.length >140){return false;}
      else {return "#"+finalResult;}
    }
}

This is the error message I encountered:

Expected an empty string to return false: expected '#' to equal false

I'm puzzled by this error, as I have covered the check for an empty string in my code.

javascript string

Answer 1

Answer №1

Two issues need to be addressed:

If the input contains only spaces, the result will still be an empty string. It is important to trim the input first before checking for emptiness.
The length test for the result is incorrect as it's done before adding the "#" symbol. The correct approach is to check if the length is greater than or equal to 140 after adding "#".

Here is the corrected code addressing these two issues:

function generateHashtag (str) {
   let text = str.trim(); // Trim the input first
   if (text == "") {return false;}
   else
     {
      const myArray = text.split(" ");
      let mot ="";
      let finalStr = ""
      for(let i=0; i< myArray.length; i++)
        {
          mot = myArray[i];
          mot = mot.charAt(0).toUpperCase() + mot.slice(1);
          finalStr =finalStr + mot;
        }
      if(finalStr.length >= 140){return false;} // Check length considering "#"
      else {return "#"+finalStr;}
    }
}

Alternatively, a solution using regular expression to extract words and "map" with "join" can achieve the same result more efficiently:

function generateHashtag (str) {
    const result = (str.trim().match(/\S+/g) ?? []).map(word =>
        word[0].toUpperCase() + word.slice(1)
    ).join("");
    return !!result && result.length < 140 && "#" + result;
}

Answer 2

Two issues need to be addressed:

If the input contains only spaces, the result will still be an empty string. It is important to trim the input first before checking for emptiness.
The length test for the result is incorrect as it's done before adding the "#" symbol. The correct approach is to check if the length is greater than or equal to 140 after adding "#".

Here is the corrected code addressing these two issues:

function generateHashtag (str) {
   let text = str.trim(); // Trim the input first
   if (text == "") {return false;}
   else
     {
      const myArray = text.split(" ");
      let mot ="";
      let finalStr = ""
      for(let i=0; i< myArray.length; i++)
        {
          mot = myArray[i];
          mot = mot.charAt(0).toUpperCase() + mot.slice(1);
          finalStr =finalStr + mot;
        }
      if(finalStr.length >= 140){return false;} // Check length considering "#"
      else {return "#"+finalStr;}
    }
}

Alternatively, a solution using regular expression to extract words and "map" with "join" can achieve the same result more efficiently:

function generateHashtag (str) {
    const result = (str.trim().match(/\S+/g) ?? []).map(word =>
        word[0].toUpperCase() + word.slice(1)
    ).join("");
    return !!result && result.length < 140 && "#" + result;
}

Anticipated a false result when comparing an empty string in JavaScript

Examples

Answer №1

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