A functional cond/case switch statement in js

switch.js

/**
 * @typedef {Function} CaseFunction
 * @param {...*} [args] - List of args provided to anonymous function
 */

/**
 * @typedef {Function} SwitchFunction
 * @param {string} [c='default'] - case string to match
 * @param {...*} [args] - args to pass to matched SwitchFunction
 * @returns {*} - Result of matching case in SwitchMap either CaseFunction called with args, or value
 */

/**
 * @typedef {Object<string, CaseFunction|*>} SwitchMap
 */

/**
 * sw.js
 *
 * This function takes a SwitchMap and returns a SwitchFunction which
 * can be called with a case property and extra args to match with
 * function
 *
 * @example
 *  sw({
 *    foo: i => i + 2,   // 5
 *    bar: 'baz',        // bar
 *    default: null,     // null
 *  })('foo', 3)
 *
 * @param {SwitchMap} cases - A map of string cases to value or CaseFunction call
 * @returns {SwitchFunction}
 */

export default cases => (c, ...args) => {
  const f = {}.hasOwnProperty.call(cases, c) 
    ? cases[c] 
    : cases.default

  return f instanceof Function ? f(...args) : f
}