JavaScript: Convert a string from camelcase

JavaScript fundamental (ES6 Syntax): Exercise-229 with Solution

Camelcase to String

Write a JavaScript program to convert a string from camelcase.

• Use String.prototype.replace() to break the string into words and add a separator between them.
• Omit the second argument to use a default separator of _.

Sample Solution:

JavaScript Code:

// Define a function 'fromCamelCase' that converts a camelCase string to snake_case by inserting a separator between words
const fromCamelCase = (str, separator = '_') =>
  // Replace occurrences where a lowercase character or digit is followed by an uppercase character with the same characters separated by the specified separator
  // Replace occurrences where one or more consecutive uppercase characters are followed by an uppercase character followed by a lowercase character or digit with the same characters separated by the specified separator
  // Convert the result to lowercase
  str
    .replace(/([a-z\d])([A-Z])/g, '$1' + separator + '$2')
    .replace(/([A-Z]+)([A-Z][a-z\d]+)/g, '$1' + separator + '$2')
    .toLowerCase();

// Test cases
console.log(fromCamelCase('someDatabaseFieldName', ' '));  
console.log(fromCamelCase('someLabelThatNeedsToBeCamelized', '-'));  
console.log(fromCamelCase('someJavascriptProperty', '_'));  

Output:

some database field name
some-label-that-needs-to-be-camelized
some_javascript_property

Visual Presentation:

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-229-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that converts a camelCase string into a space-separated, lowercased sentence.
• Write a JavaScript function that inserts spaces before uppercase letters in a camelCase string to create a human-readable sentence.
• Write a JavaScript program that transforms a camelCase identifier into a title-cased string with spaces between words.
• Write a JavaScript function that detects camelCase patterns and replaces them with a delimited format such as snake_case or spaced words.

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