pipe (从左往右）

计算 **(x+2)*5** 的值

  1. fn1 = x => x + 2
  2. fn2 = x => 5*x
  3. let result = pipe(fn1, fn2)(3)  // 25
  5. function pipe() {
  6.   // let args = Array.from(arguments)
  7.   let args = Array.prototype.slice.call(arguments)
  8.   return function(x) {
  9.     return args.reduce((result, cb) => {
  10.       return cb(result)
  11.     }, x)
  12.   }
  13. }

compose (从右往左）

  1. function compose(...args) {
  2.   return function(x) {
  3.     return args.reduceRight((result, cb) => {
  4.       return cb(result)
  5.     }, x)
  6.   }
  7. }