Lifespan

Reify the lifespan of an object, a component, whatever... Its really just like an never-failing Promise which executes its callback synchronously.

const released = {};
 
released.a = false;
let count = 0;
const a = new Lifespan().onRelease(() => released.a = true);
const i = setInterval(() => count = count + 1, 1000);
a.onRelease(() => clearInterval(i));
released.b = false;
const b = new Lifespan();
b.onRelease(() => released.b = true);
setTimeout(b.release, 5500);
b.onRelease(() => a.release());
 
released.c1 = released.c2 = released.c3 = false;
const c1 = new Lifespan().onRelease(() => released.c1 = true);
const c2 = new Lifespan().onRelease(() => released.c2 = true);
const c3 = new Lifespan().onRelease(() => released.c3 = true);
 
released.c4 = false;
const c4 = Lifespan.race(c1, c2, c3).onRelease(() => released.c4 = true);
c1.release();
released.c4.should.be.true;
 
released.d1 = released.d2 = released.d3 = false;
const d1 = new Lifespan().onRelease(() => released.d1 = true);
const d2 = new Lifespan().onRelease(() => released.d2 = true);
const d3 = Lifespan.join(d1, d2).onRelease(() => released.d3 = true);
d1.release();
released.d3.should.be.false;
d2.release();
released.d3.should.be.true;
 
setTimeout(() => {
  released.a.should.be.false;
  count.should.be.exactly(2);
}, 2200);
 
setTimeout(() => {
  released.a.should.be.true;
  count.should.be.exactly(5);
}, 6000);
 
// adds 'this.getLifespan()' method.
@lifespan
class MyComponent extends React.Component {
  ...
}

Why not just use Promise?

Promise, when properly implemented (like bluebird does) are great. Really. But sometimes you just want to reifiy "something to call later", and these calls to be synchronous.

Thats where Lifespan comes handy.

React.Component decorator

Lifespan comes with a ridiculously simple, yet very useful React.Component decorator. It adds the method this.getLifespan() to the component, which is released upon componentWillUnmount. It is lazily initialized and memoized so that the lifespan instance is only created if needed, and created once per component.

Use cases ?

EventEmitters, React Components, really anything when cleanup has to be performed at some point which is triggered manually.

Usage

This module is written in ES6/7. You will need babel to run it.