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Promise Patterns
// This file is generated by babel-plugin-transform-async-to-generator
function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }
function foo() {
var _this = this;
return _asyncToGenerator(function* () {
// Uses yield instead of await.
return true;
});
}
{
// Entrypoint should be your shim file.
"main": "index.js",
// Include files that should be published.
"files": [
"index.js",
"dist",
"src"
],
"dependencies": {
"semver": "^5.4.1"
},
"devDependencies": {
"babel-cli": "^6.24.1",
"babel-core": "^6.25.0",
"babel-plugin-transform-async-to-generator": "^6.24.1"
},
// Now you can support any node version > 6.
"engines": {
"node": ">= 6.9.1"
},
// Add the build script and prepublish script
"scripts": {
"build": "babel src/ -d dist/",
"prepublish": "yarn run build"
}
}
const semver = require('semver');
let main;
if (semver.lt(process.version, '7.6.0')) {
// Use built entrypoint for any version below 7.6.0 since
// all other versions don't natively support async functions.
// http://node.green/#ES2017-features-async-functions
main = require('dist-index.js');
} else {
main = require('src-index.js');
}
module.exports = main;
// Automatically set up your project to be transpiled using:
// node migrate-module.js <src-dir>
const fs = require('fs');
const srcFolder = process.argv[2];
if (!srcFolder) {
console.log('Please provide the name of your src folder.');
process.exit(1);
}
const raw = fs.readFileSync('./package.json');
const pkg = JSON.parse(raw);
pkg.main = 'index.js';
if (!pkg.engines) pkg.engines = {};
pkg.engines.node = '>= 6.9.1';
if (!pkg.scripts) pkg.scripts = {};
pkg.scripts.babelBuild = `babel ${srcFolder} -d dist`;
const buildCmd = 'yarn run babelBuild';
if (pkg.scripts.prepublish) {
pkg.scripts.prepublish = buildCmd + ' && ' + pkg.scripts.prepublish;
} else {
pkg.scripts.prepublish = buildCmd;
}
// Explicitly add build files
if (!pkg.files) pkg.files = [];
pkg.files.push('index.js', 'src', 'dist');
fs.writeFileSync('package.json', JSON.stringify(pkg, null, 2));
process.exit(0);
// Handle lists with Promise.all and Array.map
async function addToList(emails) {
await Promise.all(emails.map(async (email) => {
const valid = await validate(email);
if (!valid) return;
await db.list.insert({ email });
return email;
}));
}
// Promisify just one call.
const { deferred } = require('promise-callbacks');
function bar() {
const promise = deferred();
doAsync(promise.defer());
return promise;
}
// Promisify whole apis.
const { promisify } = require('promise-callbacks');
const api = {
doAsync: (cb) => {},
doMoreAsync: (cb) => {}
};
const doPromisified = promisify.all(api);
doPromisified.doAsync.then(() => {
// Celebrate
});
// Any iterator with a next method will do.
class Iterator {
next() {
if (!this.results) this.results = this.get();
return results.pop();
}
}
// Use promise iterate to defer async calls to the iterator without
// loading all results at once.
const { promiseIterate } = require('promise-iterate');
async function sendToEveryone(names) {
const cursor = new Iterator();
await promiseIterate(cursor, async (contact) => {
await sendEmail(contact.firstName, 'Hello!');
});
return true;
}
// Use promise pool for arbitrary length data to limit memory usage
// and active requests.
const PromisePool = require('@mixmaxhq/promise-pool');
async function bulkSend(names) {
const pool = new PromisePool(10);
for (let i = 0; i < names.length; i++) {
const name = names[i];
await pool.start(async () => {
send(name, 'Hello!');
});
}
await pool.flush();
return { message: 'success' };
}
async function foo() {
// Some async action.
return true;
}
module.exports = {
foo
};
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