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capitalize

TS JS Deno

Capitalizes the first letter of a string.

Use array destructuring and String.prototype.toUpperCase() to capitalize first letter, ...rest to get array of characters after first letter and then Array.prototype.join('') to make it a string again. Omit the lowerRest parameter to keep the rest of the string intact, or set it to true to convert to lowercase.

typescript
const capitalize = (str: string = "", lowerRest = false): string =>
  str.slice(0, 1).toUpperCase() +
  (lowerRest ? str.slice(1).toLowerCase() : str.slice(1));
typescript
capitalize("fooBar"); // 'FooBar'
capitalize("fooBar", true); // 'Foobar'