How do I solve this JavaScript titlecase problem with an empty string?

Question

I'm new to JavaScript and am having a bit of trouble with this problem:

Construct a function called titleCase that takes a sentence string and gives it title casing.

titleCase("this is an example") // Should return "This Is An Example"

titleCase("test") // Should return "Test"

titleCase("i r cool") // Should return "I R Cool"

titleCase("WHAT HAPPENS HERE") // Should return "What Happens Here"

titleCase("") // Should return ""

titleCase("A") // Should return "A"

This is the code I've tried:

const titleCase = function(text) {
  text = text.split(' ');

  for (let i = 0; i < text.length; i++) {
    text[i] = text[i].toLowerCase().split('');
    text[i][0] = text[i][0].toUpperCase();
    text[i] = text[i].join('');
  }

  if (text === "") {
    return ""
  }

  return text.join(' ');
}

It is passing all tests except for the empty string "" test.

Because you are comparing an array against a string, and those are 2 completely different things. Btw, if the array is empty, just let the join work. It will return an empty string. Do not make an special if for it. I mean, just remove the if (text === "") { return "" } — Jorge Fuentes González
– Jorge Fuentes González, Commented Nov 11, 2021 at 18:17
FWIW, edge cases like this can be tested from the JS console, e.g., what does ””.split() return? What are the effects of calling join on that result? Experimenting in the console provides a quick way to test assumptions (and code) without having to run a complete program/function/etc. — Dave Newton
– Dave Newton, Commented Nov 11, 2021 at 18:19
Just move your if (text === "") to the first line before text = text.split(' '); — luiscla27
– luiscla27, Commented Nov 11, 2021 at 18:25
@Andy If it’s on a web page, sure ;) But I’m not bringing in a virtual browser and selectors for my back-end app :D — Dave Newton
– Dave Newton, Commented Nov 11, 2021 at 18:41

Chong Lip Phang · Accepted Answer · 2021-11-11 18:34:59Z

1

You will need to move:

 if (text === "") {
   return ""
 }

to the first line of the function.

Here is a straightforward solution:

function titleCase(s){
   let r="";
   for (let i=0; i<s.length; i++) r+=(i==0 || s[i-1]==" ")?s[i].toUpperCase():s[i].toLowerCase();
   return r;
}
console.log(titleCase("helLo tHERE!"));
console.log(titleCase("this is an example")); //should return "This Is An Example"
console.log(titleCase("test")); //should return "Test"
console.log(titleCase("i r cool")); //should return "I R Cool"
console.log(titleCase("WHAT HAPPENS HERE")); //should return "What Happens Here"
console.log(titleCase("")); //should return ""
console.log(titleCase("A")); //should return "A"

edited Nov 11, 2021 at 18:34

answered Nov 11, 2021 at 18:21

Chong Lip Phang

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Comments

Peter Mortensen · Accepted Answer · 2022-05-18 11:09:40Z

1

You just have to declare text empty as default in the function and add the if (text === "") { condition before the for loop. So if the text is empty then before executing the for loop it will return "". Please check the following snippet:

const titleCase = function(text = '') {
    if (text === "") {
       return ""
     }
  text = text.split(' ');

  for (let i = 0; i < text.length; i++) {
    text[i] = text[i].toLowerCase().split('');
    text[i][0] = text[i][0].toUpperCase();
    text[i] = text[i].join('');
  }

  return text.join(' ');
}

console.log(titleCase());
console.log(titleCase("Hello"));
console.log(titleCase("Hello World"));

edited May 18, 2022 at 11:09

Peter Mortensen

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answered Nov 11, 2021 at 18:39

Zaid Shaikh

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Comments

Peter Mortensen · Accepted Answer · 2022-05-18 11:21:29Z

0

You can just use this simple function to solve this problem.

function titleCase(text) {
    return text.split(' ').map(word => word.charAt(0).toUpperCase() + word.slice(1)).join(' ')
}

Now let's break it down a little bit.

First I'm using text.split(' '). It converts the sentence into an array of each word.

For example,

"this is an example" became ['this', 'is', 'an', 'example']

Second, I'm using map() to convert each word to be capitalized.

word.charAt(0).toUpperCase() + word.slice(1). This is a simple way to convert a word to be capitalized. It became:

['this', 'is', 'an', 'example']``` to ```['This', 'Is', 'An', 'Example']

And finally I'm just joining each word with a space:

join(' ')

Then it returns "This Is An Example".

edited May 18, 2022 at 11:21

Peter Mortensen

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answered Nov 11, 2021 at 18:29

Hasibur Rahman

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2 Comments

Peter Mortensen Over a year ago

Does this work for an empty string? (The question says "It is passing all tests except for the empty string "" test.")

Hasibur Rahman Over a year ago

sure, you can test it

Peter Mortensen · Accepted Answer · 2022-05-18 11:08:20Z

0

You can’t modify a character with the [] notation.

To replace the first character of a string, don't do

str[0] = str[0].toUppercase()

but

str = "X" + str.substr(1)

Your function can be:

function titleCase(str) {
  return str.toLowerCase().replace(/(^|\s)[a-z]/g, (a)=>a.toUpperCase());
}

This function will:

convert all to lower case
then use a regular expression to replace letters ([a-z]) following a space (\s) or the beginning of the string (^) with its uppercase version.

edited May 18, 2022 at 11:08

Peter Mortensen

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answered Nov 11, 2021 at 18:24

Yukulélé

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2 Comments

Peter Mortensen Over a year ago

Does this work for an empty string? (The question says "It is passing all tests except for the empty string "" test.")

Yukulélé Over a year ago

@PeterMortensen yes, titleCase("") return an empty string

Peter Mortensen · Accepted Answer · 2022-05-18 11:25:29Z

-1

These console.log lines (after text = text.split(' ');) should help you understand your mistake:

const titleCase = function(text) {
  text = text.split(' ');

  console.log(text)
  console.log(text.length)

  for (let i = 0; i < text.length; i++) {
    text[i] = text[i].toLowerCase().split('');
    text[i][0] = text[i][0].toUpperCase();
    text[i] = text[i].join('');
  }
  
  if (text === "") {
    return ""
  } 

  return text.join(' ');
}

edited May 18, 2022 at 11:25

Peter Mortensen

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answered Nov 11, 2021 at 18:32

sushiLover

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2 Comments

Tyler2P Over a year ago

Instead of posting ways to debug the existing code as questions provide detailed answers that will actually provide an answer to the question.

Peter Mortensen Over a year ago

It is fine to include debugging tips, but an answer should actually answer the question, not merely be hints (unless it is a blatant homework dump). Please improve your answer. (But without "Edit:", "Update:", or similar - the answer should appear as if it was written today.)

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