模仿jquery的fadeIn、fadeOut、fadeToogle、fadeTo函数，淡入淡出效果挺不错！

淡淡的烟草味﹌ 2021-07-24 19:32 202阅读 0赞

### **需要用到自己之前写的animate函数** ###

<!DOCTYPE html>
    <html>
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=GBK">
            </head>
            <body>
    	        <div onclick="do_fadeOut()" id="div" style="width:70px;height:50px;background:skyblue;left:25%;"><p>div</p></div>
    	        <div  id="div1" style="width:70px;height:50px;background:red;display:none;"><p>div1</p></div>
    	        
    	        
    	        <button onclick="do_fadeOut()">fadeToggle Div</button>
    	        
    	        <button onclick="do_fadeIn()">fadeToggle Div1</button>
    	        
    	        <button onclick="do_fadeToggle()">fadeToggle Div</button>
    	        
    	        <button onclick="do_fadeTo()">fadeTo Div</button>
            </body>
    <script>
    /*
    	obj:dom对象
    	prop:动画参数
    	speed:执行速度 fast slow 3000等
    	func:回调函数
    */
    function animate(obj,prop,speed,func){
    	//防止重复动画事件
    	if(obj.timer) return ;
    	//定义定时器执行次数和总执行时间
    	var	limit=10,totalTime; 
    	if(typeof speed==='number'){//如果传入的是
    		totalTime = speed;
    	}else if(speed==='slow'){
    		totalTime = 600;
    	}else if(speed==='fast'){
    		totalTime = 200;
    	}else{
    		totalTime = 400;
    	}
    	
    	var time = totalTime/limit;
    	//获取属性值
    	function getStyle(obj, prop) {
    		var prevComputedStyle = document.defaultView ? document.defaultView.getComputedStyle( obj, null ) : obj.currentStyle;
    		return prevComputedStyle[prop];
    	}
    	var n=0,cache={},display,primary_cur;//cache用来缓存，省的每次都去dom获取
    	obj.timer = setInterval(function(){
    		n++;//执行次数每次递增
    		for(var p in prop){
    			if("display"===p) {
    				display = prop["display"];
    				if(display!=='none'){
    					obj.style['display'] = display;
    				}
    				delete prop["display"];
    				continue;
    			}
    			//判断是否是可以递增的属性，如果不是则直接让它生效，并从prop中删除，删除后就不用每次任务都执行它
    			var reg = /^(\d)+(px$)?/;//数字和像素这样的判定为可以递增的属性
    			if(!reg.test(prop[p])){
    				obj.style[p] = prop[p];
    				delete prop[p];
    				continue;
    			}
    			
    			var value,opacityFlag=(p == "opacity")?true:false;
    			var cur = 0;
    			if(cache[p+"_cur"]){//从缓存中取
    				cur = cache[p+"_cur"];
    				value = cache[p+"_value"];
    			}else{
    				value = prop[p];
    				if(opacityFlag) {
    					//如果本来是隐藏的则cur默认就是0
    					if(getStyle(obj, 'display')!=='none'){
    						cur = Math.round(parseFloat(getStyle(obj, p)) * 100);
    					}
    				} else {
    					cur = parseInt(getStyle(obj, p));
    					//处理100px的格式
    					(typeof value==='string') && (value=value.replace(/px$/,""));
    				}
    				primary_cur=cur;
    				cache[p+"_value"] = value;
    			}
    			
    			var incre ;
    			if(cache[p+'_increment']){//如果缓存中有则从中取
    				incre = cache[p+'_increment'];
    			}else{
    				if(opacityFlag){
    					incre = (value*100-cur)/limit;//计算每次变化值
    				}else{
    					incre = (value-cur)/limit;//计算每次变化值
    				}
    				cache[p+'_increment']= incre;
    			}
    			//缓存起来，这样就不用每次都去dom中获取了。
    			cache[p+"_cur"] = cur + incre;
    			
    			if (opacityFlag) {
    				//obj.style.filter = "alpha(opacity : '+(cur + incre)+' )";
    				obj.style.opacity = (cur + incre)/100 ;
    			}else {
    				obj.style[p] = cur + incre + "px";
    			}
    		}
    		//如果达到了最大执行次数，要清除定时器，并执行回调函数
    		if(n==limit){
    			if(display==='none'){
    				obj.style['display'] = 'none';
    			}
    			//清除定时器
    			clearInterval(obj.timer);
    			obj.timer=undefined;
    			func();
    		}
    	},time)
    	
    }
    var div = document.getElementById("div");
    var div1 = document.getElementById("div1");
    
    
    /*function do_animate(){
    	animate(div,{width:'400px',height:400,opacity: 0,background:'red'},2000,function(){
    	console.log('finished')
    });
    }*/
    
    /*
    	obj:dom对象
    	speed:执行速度 fast slow 3000等
    	func:回调函数
    */
    
    function fadeOut(obj,speed,func){
    	animate(obj,{opacity: 0,display:'none'},speed,func);
    }
    
    function fadeIn(obj,speed,func){
    	animate(obj,{opacity: 1,display:'block'},speed,func);
    }
    
    function fadeToggle(obj,speed,func){
    	if(obj.style.display==='none'){
    		fadeIn(obj,speed,func);
    	}else{
    		fadeOut(obj,speed,func);
    	}
    } 
    function fadeTo(obj,speed,opacity,func){
    	if(opacity>0 && obj.style.display==='none'){
    		animate(obj,{opacity: opacity,display:'block'},speed,func);
    	}else{
    		animate(obj,{opacity: opacity},speed,func);
    	}
    }
    
    //执行隐藏
    function do_fadeOut(){
    	fadeOut(div,1000,function(){
    		console.log('fadeOut_finished')
    	})
    }
    
    //执行显示
    function do_fadeIn(){
    	fadeIn(div1,2000,function(){
    		console.log('fadeIn_finished')
    	})
    }
    
    function do_fadeToggle(){
    	fadeToggle(div,1000,function(){
    		console.log('fadeToggle_finished')
    	})
    }
    
    
    function do_fadeTo(){
    	fadeTo(div,"slow",0.15,function(){
    		console.log('fadeTo_finished')
    	});
    }
    
    </script>
    </html>