generate-index.js

// this helper script was copied in from newts to automatically
// generate your index.ts in your src folder. Once that is transpiled,
// you'll get an index.js and index.d.ts in the dist folder and the
// initially-generated index.js and index.d.ts in the base of your
// package will defer to these, providing for a clean import of
// everything exported from base files in your src folder
const path = require("path");
const fs = require("fs");
const srcDir = "src";

function readdir(at) {
    return new Promise((resolve, reject) => {
        fs.readdir(at, (err, result) => err ? reject(err) : resolve(result));
    });
}

function writeFile(at, contents) {
    return new Promise((resolve, reject) => {
        fs.writeFile(at, contents, { encoding: "utf-8" }, err =>
            err ? reject(err) : resolve()
        )
    });
}

async function hasHashBang(f) {
    const
        readFile = fs.promises.readFile,
        contents = await readFile(f, "utf8");
    return contents.indexOf("#!") === 0;
}

async function filterHashBanged(paths) {
    const result = [];
    for (const p of paths) {
        if (await hasHashBang(path.join(srcDir, p))) {
            continue;
        }
        result.push(p);
    }
    return result;
}

(async () => {
    const cwdContents = await readdir(".");
    if (cwdContents.indexOf(srcDir) === -1) {
        throw new Error(`No local '${srcDir}' folder -- nothing to do`);
    }
    const
        tsFiles = (await readdir(srcDir))
            .filter(f => f.match(/\.ts$/)),
        nonExecutables = await filterHashBanged(tsFiles),
        target = path.resolve(path.join("src", "index.ts")),
        output = nonExecutables.sort()
            .map(f => `export * from "./${ f.replace(/\.ts$/, "") }";`)
            .join("\n");
    await writeFile(
        target,
        `// this is a generated file: do not edit\n${ output }\n`
    );
    console.log(`Updated index at: ${ target }`);
})();