Optional.js
A container object that wraps possibly undefined values in JavaScript - inspired by Java Optionals
Optional.ofNullable(promptForUserName)
.map(getUserId)
.filter(verify)
.ifPresent(login);
Features
- Runs in browser and Node
- Full Java 8 Optional API is supported, and partial Java 9 API implemented (everything minus stream())
- Zero dependencies
- TypeScript type definitions included
- Lightweight (<1.0 KB minified, gzipped)
Installation
Download the latest release from GitHub or from NPMvia npm:
$ npm install optional-js
then just require in node:
const Optional = require('optional-js');
const emptyOptional = Optional.empty();
alternatively, use the browser compatible build in the
./dist
directory of the npm packageNot using a module loader? Include the script, and the browser global
Optional
will be added to window.Usage
Java docs - Java 9 OptionalsTSDocs - index.d.ts
JS Example:
// "login.js"
const Optional = require('optional-js');
// Define some simple operations
const getUserId =
username => username === 'root' ? 1234 : 0;
const verify =
userId => userId === 1234;
const login =
userId => console.log('Logging in as : ' + userId);
// Declare a potentially undefined value
const username = process.argv[2];
// Wrap username in an Optional, and build a pipeline using our operations
Optional.ofNullable(username)
.map(getUserId)
.filter(verify)
.ifPresent(login);
Then, from the terminal...
$ node login.js root
"Logging in as : 1234"
````
# Building
download:
``` bash
git clone git@github.com:JasonStorey/Optional.js.git
enter the directory, and install dependencies:
cd Optional.js && npm install
build:
npm run build
Testing
run the tests:
npm test
Contributing
Found a bug or missing feature? Please open an issue!Send your feedback. Send your pull requests. All contributions are appreciated!
License
Optional.js may be freely distributed under the MIT license - LICENSE