Javascript - TitleCase

Title Case is a type of capitalization in which the first letter of a word is capitalized, and the rest of the letters are lowercase.

This rule might not apply to non-relevant terms from articles, pronouns classes. We’ll consider any word, regardless of whether it’s an article or a pronoun.

Titling one word

The following function converts a single word into the Title Case:

function titleCase(word) {
   return word.charAt(0).toUpperCase() + word.substr(1).toLowerCase();
}

The code is self-explanatory.

In action

> titleCase("dm8ty")
"Dm8ty"

> titleCase("i am dm8tyProgrammer")
"I am dm8tyProgrammer"

Titling all the words in a sentence.

The following function converts each word of a given sentence to TitleCase:

function titleCase(sentence)  {
   return sentence.replace(/w+/g, word => word.charAt(0).toUpperCase() + word.substr(1).toLowerCase());
}

The code takes each matching word (\w+) and runs the titling expression over it.

In action

> titleCase("dm8ty")
"Dm8ty"

> titleCase("i am dm8tyProgrammer")
"I Am Dm8typrogrammer"

Adding TitleCase as an extension of String

The following code illustrates adding the title case method to the existing string construct:

String.prototype.toTitleCase = function () {
  return this.replace(/w+/g, word => word.charAt(0).toUpperCase() + word.substr(1).toLowerCase());
};

We just attached the last piece of code to the String prototype.

In action

> "dm8ty".toTitleCase()
"Dm8ty"

> "i am dm8tyProgrammer".toTitleCase()
"I Am Dm8typrogrammer"

Excluding Titling of irrelevant words

Maintain a collection (array or set) of irrelevant words, and check the presence of the word in the collection before titling.

// make a collection of words
let irrelevance = ['a', 'an', 'the', 'am']


String.prototype.toTitleCase = function() {

  // check the presence of the word in the irr collections and, if present, exclude titling.
  return this.replace(/w+/g, word => irrelevance.includes(word)? word : word.charAt(0).toUpperCase() + word.substr(1).toLowerCase());
};

In action

> "dm8ty".toTitleCase()
"Dm8ty"

> "i am dm8tyProgrammer".toTitleCase()
"I am Dm8typrogrammer"

What if “The” article falls at the beginning of a sentence?