【逐日一包0019】mem

2019年8月20日 133次阅读 来源: 王炜

[github地点：https://github.com/ABCDdouyae…]

mem

用于经由过程缓存具有雷同输入的挪用效果来加快连续函数挪用的优化

一般用法 (支撑基于promise的异步函数挪用)
const mem = require('mem');

let i = 0;
let a = () => i++;

let mem_a = mem(a);

mem_a();
console.log(i);//1
mem_a();
console.log(i);//1
mem_a(10);
console.log(i);//2
mem_a();
console.log(i);//2
mem_a(11);
console.log(i);//3
let b = async () => j++;
let mem_b = mem(b);

(async ()=> {
  await mem_b();
  console.log(j);//1
  await mem_b();
  console.log(j);//1
  await mem_b(10);
  console.log(j);//2
})();
第二参数用法

用法：mem(Function, options|object)

  • maxAge：设置缓存时长，默许infinity
const mem = require('mem');
const got = require('got');
const delay = require('delay');
 
const memGot = mem(got, {maxAge: 1000});
 
(async () => {
    await memGot('sindresorhus.com');
 
    // This call is cached
    await memGot('sindresorhus.com');
 
    await delay(2000);
 
    // This call is not cached as the cache has expired
    await memGot('sindresorhus.com');
})();
  • cacheKey：默许一切参数雷同才启用缓存数据，但你也能够设置只缓存第一个参数（也就是只需第一个参数雷同，就采纳缓存值）
let c = (a, b) => k++;
let mem_c = mem(c);
mem_c(1, 2);
console.log(k);//1
mem_c(1, 3);
console.log(k);//2
mem_c(1, 3);
console.log(k);//2

let d = (a, b) => l++;
let mem_d = mem(d, {cacheKey: x => JSON.stringify(x)});
mem_d(1, 2);
console.log(l);//1
mem_d(1, 3);
console.log(l);//1
mem_d(2, 3);
console.log(l);//2
  • cache：设置缓存体式格局，默许new Map(),比方.has(key), .get(key), .set(key, value), .delete(key), and optionally .clear(). You could for example use a WeakMap instead or quick-lru for a LRU cache.
  • cachePromiseRejection：缓存promise的reject的返回，默许为false
  • mem.clear(fn)：消灭某个函数的缓存数据
    原文作者：王炜
    原文地址: https://segmentfault.com/a/1190000017140370
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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