memo

记忆化函数

使用方法

用 memo 包装函数以获得一个自动返回已计算值的函数。

import * as _ from "radashi";

const timestamp = _.memo(() => Date.now());

const now = timestamp();
const later = timestamp();

now === later; // => true

过期时间

您可以选择传递一个 ttl（生存时间）来使记忆化结果过期。在版本 10 之前的版本中，如果未指定，ttl 的值为 300 毫秒。

import * as _ from "radashi";

const timestamp = _.memo(() => Date.now(), {
  ttl: 1000, // 毫秒
});

const now = timestamp();
const later = timestamp();

await _.sleep(2000);

const muchLater = timestamp();

now === later; // => true
now === muchLater; // => false

键函数

您可以选择自定义记忆化时值的存储方式。

const timestamp = _.memo(
  ({ group }: { group: string }) => {
    const ts = Date.now();
    return `${ts}::${group}`;
  },
  {
    key: ({ group }: { group: string }) => group,
  }
);

const now = timestamp({ group: "alpha" });
const later = timestamp({ group: "alpha" });
const beta = timestamp({ group: "beta" });

now === later; // => true
beta === now; // => false