Ember observers mixin

attrs-observer.js

import Ember from 'ember';
export default Ember.Mixin.create({
    lastChangedAttrs: null,
    init() {
        this.resetLastChangedAttrs();
        this.initObservers();
        this._super(...arguments);
    },
    didChangeAttrs() {
        console.log('not implemented');
    },
    createObserverFor(propertyName) {
        return function (target, key) {
            this.addChangedAttribute(propertyName);
        }.bind(this);
    },
    initObservers() {
        (this.get('didChangeAttrsConfig.attrs') || []).forEach((attrName) => {
            let observerName = `${attrName}@observer`;
            this[observerName] = this.createObserverFor(attrName);
            this.addObserver(attrName, this, observerName);
        });
    },
    didUpdateAttrs() {
        this.didChangeAttrs(this.lastChangedAttrs);
        this.resetLastChangedAttrs();
        this._super(...arguments);
    },
    addChangedAttribute(name) {
        this.lastChangedAttrs[name] = this.get(name);
    },
    resetLastChangedAttrs() {
        this.lastChangedAttrs = {};
    }
});