Expoアプリのリリース時にversionCodeとbuildNumberを更新するやつ。package.jsonと同じディレクトリに置いておきます。

package.ts

var packagejson = require(__dirname + "/package.json");

interface Package {
  name: string;
  versionName: string;
  versionNameWithoutBuild: string;
  versions: number[];
  versionCode: number;
}

const versionNameWithoutBuild: string = packagejson.version.replace(/-build\.?\d+/, "");
const versions: number[] = packagejson.version.match(/\d+/g);

export default {
  name: packagejson.name,
  versionName: packagejson.version,
  versionNameWithoutBuild,
  versions,
  versionCode: Number(versions[0]) * 1000000 + Number(versions[1]) * 10000 + Number(versions[2]) * 100 + Number(versions[3]),
} as Package;

update_version.ts

/**
 * package.jsonのバージョンをapp.jsonのversionCodeとbuildNumberに配布するやつ
 * package.jsonに`"version": "1.2.3-build.3"`みたいに書いておくと、
 * ```
 * "version": "1.2.3",
 * "versionCode": 1020303,
 * "buildNumber": "1020303",
 * ```
 * のようにapp.jsonが書き換えられます。
 *
 * 使い方
 * $ ts-node update_version.ts
 */

import fs from "fs";
import packagejs from "./package";

const appJsonPath = __dirname + "/app.json";

const t = fs.readFileSync(appJsonPath, "utf-8");

const out = t
    .replace(/"version": "\d+\.\d+(\.\d+)?(-build\.\d+)?"/, `"version": "${packagejs.versionNameWithoutBuild}"`)
    .replace(/"versionCode": \d+/, `"versionCode": ${packagejs.versionCode}`)
    .replace(/"buildNumber": "\d+"/, `"buildNumber": "${packagejs.versionCode}"`);

fs.writeFileSync(appJsonPath, out);