Switch String Case. Coverts camelCase or PascalCase to kebab-case or snake_case or any delimited string and vice versa,

switch-case.js

const camelCaseToDelimitedString = (string, delimiter = '-') => 
    string.replace(/([a-z0-9]|(?<!^)(?=[A-Z]))([A-Z])/g, '$1'+delimiter+'$2').toLowerCase();

const delimitedStringToCamelCase = (string, delimiter = '-') =>
    string.replace(new RegExp(delimiter + '([a-z])', 'g'), (m, c) => c.toUpperCase());

/**
 * Examples
 */
console.log(camelCaseToDelimitedString('helloWorld'));
console.log(camelCaseToDelimitedString('helloWorld', '_'));
console.log(camelCaseToDelimitedString('HelloWorld'));
console.log(camelCaseToDelimitedString('HelloWorld', '_'));
console.log(delimitedStringToCamelCase('hello-world'));
console.log(delimitedStringToCamelCase('hello, world', ', '));