use Object.observe to avoid callback hell

index,js

	/**
	 * push callback function into arr array  
	 * and observe the arr
	 * pretty cool!
	**/
	var request = require('request');
	var options = {
		url: "http://www.baidu.com"
	};
	var t1 = new Date();
	
	var arr=[];
	
	arr.push(function(err,res,body){
		console.log(body);
	});
	
	
	Object.observe(arr,function(changes){
		console.log(123);
		arr[0].apply(this,arr.slice(1));
	},['updated']);
	
	
	request(options,function(){
		var args = [].slice.call(arguments);
		args.map(function(item){
			arr.push(item);
		});
	});