compose javascript

[xiaotiandada]

2020-02-26 22:54:15

在阅读某段代码的时候,了解到了compose 但是似乎不止redux 很多工具库都用到了这个function

code

/**
 * Composes single-argument functions from right to left. The rightmost
 * function can take multiple arguments as it provides the signature for
 * the resulting composite function.
 *
 * @param {...Function} funcs The functions to compose.
 * @returns {Function} A function obtained by composing the argument functions
 * from right to left. For example, compose(f, g, h) is identical to doing
 * (...args) => f(g(h(...args))).
 */

export default function compose(...funcs) {
  if (funcs.length === 0) {
    return arg => arg
  }

  if (funcs.length === 1) {
    return funcs[0]
  }

  return funcs.reduce((a, b) => (...args) => a(b(...args)))
}

以前的写法:

fn1(fn2(fn3(fn4(fnN(...)))))

现在的写法:

compose(fn1, fn2, fn3, fn4, fnN)(...)

相关链接:

redux

Use function composition in JavaScript

redux之compose

redux compose 详解