promise-like.js

/*
* @Author: sushiljainam
* @Date:   2018-01-03 12:20:39
* @Last Modified by:   sushiljainam
* @Last Modified time: 2018-01-03 12:31:37
*/

//----------------------- common

var afterLongWork = function () {
	console.log('after longWork do this')
}

//------------------------- with callback

function longWork(cb) {
	setTimeout(function () {
		console.log('longWork finished');
		cb()
	}, 2000);
}

longWork(afterLongWork)

//------------------------ promise like

function longWork() {
	var self = this;
	this.then = function (cb) {
		this.afterSuccess = cb;
	}
	setTimeout(function () {
		console.log('longWork finished');
		self.afterSuccess();
	}, 2000)
	return this;
}

longWork().then(afterLongWork);

//------------------------ hybrid

function longWork(cbg) {
	var self = this;
	this.afterSuccess = cbg;
	this.then = function (cb) {
		this.afterSuccess = cb;
	}
	setTimeout(function () {
		console.log('longWork finished');
		self.afterSuccess();
	}, 2000)
	return this;
}

longWork(afterLongWork)

longWork().then(afterLongWork);

//------------------------