froebel/case.mjs

TypeScript utility library

/** Upper-case first letter of string. */
export const capitalize = str => str[0].toUpperCase() + str.slice(1);
/** Lower-case first letter of string */

export const uncapitalize = str => str[0].toLowerCase() + str.slice(1);
/** Strictly typed `String.toUpperCase()`. */

export const upper = str => str.toUpperCase();
/** Strictly typed `String.toLowerCase()`. */

export const lower = str => str.toLowerCase();
/**
 * Transforms a variable name to snake case.
 *
 * Note: The rules for transforming anything to snake case are somewhat vague.
 * So use this only for very simple names where the resulting value is
 * absolutely unambiguous. For more examples of how names are transformed, have
 * a look at the test cases.
 *
 * @example
 * ```
 * snake('fooBar') // 'foo_bar'
 * ```
 */

export const snake = str => str.replace(/(\p{L})-(?=\p{L})/gu, "$1_").replace(/(^|_)(\p{Lu})(?!\p{Lu})/gu, (_, a, b) => `${a}${b.toLowerCase()}`).replace(/([^\p{Lu}])(\p{Lu})(?=\p{Lu})/gu, (_, a, b) => `${a}_${b}`).replace(/([^\p{Lu}_0-9])(\p{Lu})/gu, (_, a, b) => `${a}_${b.toLowerCase()}`).replace(/(\p{Lu}[^\p{L}_]*)(\p{Ll})/gu, (_, a, b) => `${a}_${b}`);
/**
 * Transforms a variable name to kebab case.
 *
 * Note: The rules for transforming anything to kebab case are somewhat vague.
 * So use this only for very simple names where the resulting value is
 * absolutely unambiguous. For more examples of how names are transformed, have
 * a look at the test cases.
 *
 * @example
 * ```
 * kebab('fooBar') // 'foo-bar'
 * ```
 */

export const kebab = str => str.replace(/(\p{L})_(?=\p{L})/gu, "$1-").replace(/(^|-)(\p{Lu})(?!\p{Lu})/gu, (_, a, b) => `${a}${b.toLowerCase()}`).replace(/([^\p{Lu}])(\p{Lu})(?=\p{Lu})/gu, (_, a, b) => `${a}-${b}`).replace(/([^\p{Lu}\-0-9])(\p{Lu})/gu, (_, a, b) => `${a}-${b.toLowerCase()}`).replace(/(\p{Lu}[^\p{L}\-]*)(\p{Ll})/gu, (_, a, b) => `${a}-${b}`);
/**
 * Transforms a variable name to camel case.
 *
 * Note: The rules for transforming anything to camel case are somewhat vague.
 * So use this only for very simple names where the resulting value is
 * absolutely unambiguous. For more examples of how names are transformed, have
 * a look at the test cases.
 *
 * @example
 * ```
 * camel('foo_bar') // 'fooBar'
 * ```
 */

export const camel = str => str.replace(/^\p{Lu}/u, v => v.toLowerCase()).replace(/([^_-][_-]*)[_-](\p{L})/gu, (_, a, b) => a + b.toUpperCase());
/**
 * Transforms a variable name to pascal case.
 *
 * Note: The rules for transforming anything to pascal case are somewhat vague.
 * So use this only for very simple names where the resulting value is
 * absolutely unambiguous. For more examples of how names are transformed, have
 * a look at the test cases.
 *
 * @example
 * ```
 * pascal('foo_bar') // 'FooBar'
 * ```
 */

export const pascal = str => capitalize(camel(str));
/**
 * Transforms a variable name to screaming snake case.
 *
 * @see {@link snake}
 *
 * @example
 * ```
 * screamingSnake('fooBar') // 'FOO_BAR'
 * ```
 */

export const screamingSnake = str => upper(snake(str));
/**
 * Transform a variable name to `targetCase`
 *
 * @see {@link snake}
 * @see {@link kebab}
 * @see {@link camel}
 * @see {@link pascal}
 * @see {@link screamingSnake}
 */

export const transformCase = (str, targetCase) => {
  if (!(targetCase in converters)) {
    throw Error(`can't convert to ${targetCase} case`);
  }

  return converters[targetCase](str);
};
const converters = {
  camel,
  kebab,
  pascal,
  snake,
  "screaming-snake": screamingSnake
};