Simple observer class decorator for preact and nx-js/observer-util.

simple-observer.ts

import { observe, unobserve } from "@nx-js/observer-util";

export const observer = (klass) => {
    let kp = klass.prototype, 
        cwm = kp.componentWillMount,
        cdu = kp.componentDidUnmount;
    kp.componentWillMount = function() {
        this.render = observe(this.render, { scheduler: () => this.setState(), lazy: true })
        cwm && cwm.apply(this, arguments);
    }
    kp.componentDidUnmount = function() {
        unobserve(this.render);
        cdu && cdu.apply(this, arguments);
    }
    return klass;
}

/// Example Usage

let thing = observable({ foo: "This is foo's data"});

@observer
class Foo extends Component {
    render() {
        return <h1>{thing.foo}</h1>
    }
}