JavaScrip两个函数的设置为回调

1.javascript异步编程之回调函数
 function fn2(data){
     alert(data)
 }
 function fn1(callback){
     var data = 12+1;
     callback && callback(data)//data是fn1的操作结果
 }
 fn1(fn2);

	function fn2(total){
			alert("执行完了fn1")
			alert(total);
	}
	function fn1(arr,callback){
		var total = arr.reduce(function(a,b,index,arr){
		return a + b;
	})
	callback && callback(total)//data是fn1的操作结果
}

fn1([1,2,3,4,5],fn2);

　

2.JavaScript异步编程之事件驱动

function fn1(arr){
var total = arr.reduce(function(a,b,index,arr){
return a+b;
})
fn1.trigger('done',total)
}
function fn2(total){
console.log("fn1执行完毕")
console.log(total)
}
_.extend(fn1,Backone.Events);
fn1.on('done',fn2);
fn1([1,2,3,4,5]);

　　3.JavaScript异步编程之发布订阅

function fn1(arr){
			var total = arr.reduce(function(a,b,index,arr){
				return a+b;
			})
			fn1.publish('done',total)
		}
		function fn2(total){
			console.log("fn1执行完毕")
			console.log(total)
		}
		$.subscribe("done",fn2);
		fn1([1,2,3,4,5]);

　　4.JavaScript异步编程之Promise

function fn1(arr){
	var dtd = $.Deferred();
	window.setTimeout(function(){
	var total = arr.reduce(function(a,b,index,arr){
		return a+b;
	})
	dtd.resolve(total);
},1000)
		return dtd
}
	function fn2(total){
		console.log("fn1执行完毕")
		console.log(total)
	}
	fn1([1,2,3,4,5]).then(fn2);