Promises, Promises Everywhere
A utility library that is all about JavaScript Promises!
About
I am always fascinated with things you can manipulate by using Promises. However, I was repeating my Promise conventions in every project or even multiple modules within the same project. Therefore, I decided that I should just write it once and use it as a library across all my projects.
Utilities
fake
A method that mimics an async function behavior. It takes an options configuration object as parameter, and returns either a resolved, or reject, promise.
interface Config {
reject?: boolean;
timeout?: number;
response?: any;
}
Usage:
fake({
timeout: 1500, // in Milliseconds, default timeout is 200
response: { a: 1, b: 2 }, // Can be whatever you want it to be.
reject: false, // Default value will always be false.
});
// with async/await
async function doSomething() {
const myPromiseResponse = await fake({
response: 'Got it',
});
}
aggregate
A method that accepts a keyByArguments map, and a callback function. It will return an object where every key will contain the resolved or rejected promise from the callback function.
Usage:
const callbackFunction = async (id, filter) => {
const response = await fetch('/api/some-path', {
query: {
id,
filter,
},
}).then(res => res.json());
return response;
};
async function DoSomething() {
const keyByArgs = {
first: {
id: '123',
filter: false,
},
second: {
id: '234',
filter: true,
},
};
const myPromiseResponse = await aggregate(keyByArgs, callbackFunction);
}
wrap
A method that accepts a callback function, and wraps it with a Promise so it can be used within any async/await function closure.
Usage:
const savePost = (method, body) => {
return fetch('/api/some-path', {
method,
body,
}).then(res => res.json());
};
async function DoSomething(blogPost) {
const saveBlogPost = wrap(savePost);
const savedBlogPost = await saveBlogPost(
blogPost.id ? 'PUT' : 'POST',
blogPost
);
return savedBlogPost;
}
Special Thanks
The people who are responsible for TSDX. A great utility to help you bootstrap a new npm library with TypeScript, Rollup and Jest testing framework. See TSDX on Github.