Capitalize string

OSCC · JavaScript, String · Nov 1, 2020

Capitalizes the first letter of a string.

  • Use array destructuring and String.prototype.toUpperCase() to capitalize the first letter of the string.
  • Use Array.prototype.join() to combine the capitalized first with the ...rest of the characters.
  • Omit the lowerRest argument to keep the rest of the string intact, or set it to true to convert to lowercase.
const capitalize = ([first, ...rest], lowerRest = false) =>
  first.toUpperCase() +
  (lowerRest ? rest.join('').toLowerCase() : rest.join(''));
capitalize('fooBar'); // 'FooBar'
capitalize('fooBar', true); // 'Foobar'

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