JavaScript: Check a string is in Pascal case

JavaScript String: Exercise-56 with Solution

A PascalCase naming convention capitalizes the first letter of each compound word in a variable. It is a best practice in software development to use descriptive variable names.
Write a JavaScript function to check whether a string is in Pascal case or not.
Test Data:
("XmlStream") -> true
("IOStream") -> true
("javascript") -> false
(12356) -> "It must be a string."

Sample Solution:

JavaScript Code:

// Define a function named 'test' with a single parameter 'word'
const test = (word) => {
  // Check if the input parameter 'word' is not a string
  if (typeof word !== 'string')
  {
    // Return a message if the input is not a string
    return 'It must be a string.'
  }
  // Define a regular expression pattern to match words starting with an uppercase letter followed by zero or more letters (uppercase or lowercase)
  const pattern = /^[A-Z][A-Za-z]*$/
  // Test if the input word matches the defined pattern
  return pattern.test(word)
}

// Test the 'test' function with different input strings and output the result
console.log(test("XmlStream"))        // true
console.log(test("IOStream"))         // true
console.log(test("IEnumerable"))      // true
console.log(test("javascript"))       // false
console.log(test(12356))              // It must be a string. 

Output:

true
true
true
false
It must be a string.

Explanation:

In the exercise above,

• The function "test()" is defined using arrow function syntax, taking a single parameter named 'word'.
• It checks if the input parameter 'word' is not a string using the 'typeof' operator. If it's not a string, the function returns a message indicating that it must be a string.
• If the input is a string, the function defines a regular expression pattern (/^[A-Z][A-Za-z]*$/) to match words that start with an uppercase letter followed by zero or more letters (uppercase or lowercase).
• The function then tests if the input word matches the defined pattern using the "test()" method of the regular expression object.
• The function returns 'true' if the word matches the pattern and 'false' otherwise.

Flowchart:

Live Demo:

See the Pen javascript-string-exercise-56 by w3resource (@w3resource) on CodePen.

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