@kisaragi-hiu/cached-fetch

A caching function designed for caching fetch GET responses on disk in a command line program.

I keep rewriting this logic in multiple projects, so I'm making it a package.

Usage

import { cached } from "@kisaragi-hiu/cached-fetch";

const text = await cached(
  "myCacheKey",
  () => fetch("https://example.com")
)

This persists the text response in os.tmpdir and should stay around until the next reboot.

Signature: cached(key, fetcher)

Arguments:

• key: the key of the value. Subsequent calls with the same key will return the cached value.
• fetcher: a function doing work that should be cached. This should return any of these:

  • Promise<{text: () => string | Promise<string>}, a promise of an object whose “text” property is a function returning a string or a promise of a string.

    This covers both a Promise<Response> from fetch, and also ProcessPromise from zx. So this works:

    const value = await cached("key1", () => fetch("https://example.com"))
    
    import {$} from "zx"
    const output = await cached("key2", () => $`sleep 1 && echo "slow process demo"`)

  • a Promise<string>

  • a string. In this case the whole call is sync.

    const output = cached("key4", () =>
      spawnSync("ls", { stdio: "pipe", encoding: "utf-8" }).stdout,
    );