git-cat-file/bin/git-rev-parse-js.ts

A pure-JavaScript implementation of `git cat-file -p` for Node.js.

#!/usr/bin/env node

/**
 * https://github.com/kawanet/git-cat-file
 *
 * Executed directly by Node via its built-in TypeScript type-stripping
 * (Node >= 22). No bundling step is involved for CLI entry points.
 */

import {promises as fs} from "node:fs"
import {parseOptions} from "../lib/cli-lib.ts"
import {openLocalRepo} from "../lib/index.ts"

const longParams = {
    help: true,
}

const shortParams = {
    C: "path", // change directory
    h: true, // show help
}

async function CLI(args: string[]) {
    const options = parseOptions({
        long: longParams,
        short: shortParams,
        args: args,
    })
    args = options.args

    const {C} = options.short
    if (C) process.chdir(C)

    if (await fs.readdir(".git").catch((): null => null)) {
        process.chdir(".git")
    }

    const {help} = options.long
    const {h} = options.short
    if (help || h) {
        process.stderr.write(`Usage:\n`)
        showHelp()
        process.exit(1)
    }

    const repo = openLocalRepo(".")

    while (args.length) {
        const revision = args.shift()
        const obj = await repo.getObject(revision)
        const commit_id = obj?.oid
        if (!commit_id) {
            process.stderr.write(`Invalid revision: ${revision}\n`)
            showHelp()
            process.exit(1)
        }

        process.stdout.write(`${commit_id}\n`)
    }
}

function showHelp() {
    process.stderr.write(`  git-rev-parse-js [-C path] <args>...\n`)
}

CLI(process.argv.slice(2)).catch(console.error)