Function getParamNames

src/function.ts:18–30

(func: (...args: any[]) => any, cache?: boolean)

 * @return {Array} names
 */
export function getParamNames(func: (...args: any[]) => any, cache?: boolean): string[] {
  const type = typeof func;
  assert.equal(type, 'function', `The "func" must be a function. Received type "${type}"`);

  cache = cache !== false;
  if (cache && '__cache_names' in func) {
    return func.__cache_names as string[];
  }
  const str = func.toString();
  const names = str.slice(str.indexOf('(') + 1, str.indexOf(')')).match(/([^\s,]+)/g) || [];
  Reflect.set(func, '__cache_names', names);
  return names;
}