本文实例为大家分享了js实现淘宝放大镜的具体代码，供大家参考，具体内容如下
描述：
JS面向对象——淘宝放大镜实现
图片的引用是一个大图，一个小图
传输用的ajax，记得改成自己的ip地址，js和html都改一下
效果：
实现：
js文件：
LoadMethod.js
class LoadMethod{ static get LOAD_IMG_FINISH(){ return "load_img_finish"; } static init(sourceList){ let img=new Image(); img.num=0; img.sourceList=sourceList; img.targetList={}; img.addEventListener("load",LoadMethod.loadHandler); img.src=sourceList[0]; } static loadHandler(e){ let images=this.cloneNode(false); let name=this.sourceList[this.num]; name=name.slice(name.lastIndexOf("/")+1,name.lastIndexOf(".")); this.targetList[name]={src:images.src,elem:images,width:images.width,height:images.height}; this.num++; if(this.num>this.sourceList.length-1){ this.removeEventListener("load",LoadMethod.loadHandler); let evt=new Event(LoadMethod.LOAD_IMG_FINISH); evt.targetList=this.targetList; document.dispatchEvent(evt); return; } this.src=this.sourceList[this.num]; }}class Drag{ static dragElem(elem,rect,parent){ Drag.drageHandler=Drag.mouseHandler.bind(elem); elem.rect=rect; elem.parent=parent; elem.addEventListener("mousedown",Drag.drageHandler); } static removeDrag(elem){ elem.removeEventListener("mousedown",Drag.drageHandler); Drag.drageHandler=null; } static mouseHandler(e){ if(e.type==="mousedown"){ this.addEventListener("mouseup",Drag.drageHandler); this.offsetPoint={x:e.offsetX,y:e.offsetY}; document.addEventListener("mousemove",Drag.drageHandler); }else if(e.type==="mousemove"){ if(!this.rect){ this.rect=this.parent.getBoundingClientRect(); } let obj={ left:e.x-this.offsetPoint.x-this.rect.left+"px", top:e.y-this.offsetPoint.y-this.rect.top+"px", position:"absolute" }; Object.assign(this.style,obj); let elemRect=this.getBoundingClientRect(); if(elemRect.left<this.rect.left){ this.style.left="0px"; } if(elemRect.right>this.rect.right){ this.style.left=this.rect.right-elemRect.width-this.rect.left+"px"; } if(elemRect.top<this.rect.top){ this.style.top="0px"; } if(elemRect.bottom>this.rect.bottom){ this.style.top=this.rect.bottom-elemRect.height-this.rect.top+"px"; } let evt=new Event(Drag.ELEM_MOVE_EVENT); evt.point={x:this.offsetLeft,y:this.offsetTop}; this.dispatchEvent(evt); }else if(e.type==="mouseup"){ this.removeEventListener("mouseup",Drag.drageHandler); document.removeEventListener("mousemove",Drag.drageHandler); } } static get ELEM_MOVE_EVENT(){ return "elem_move_event"; }}
ZoomClasses.js
class ZoomClasses{ constructor(panrent){ this.bindHandler=this.loadFinishHandler.bind(this); document.addEventListener(LoadMethod.LOAD_IMG_FINISH,this.bindHandler); this.zoomView=this.createView(); panrent.appendChild(this.zoomView); } createView(){ if(this.zoomView) return this.zoomView; let p=document.createElement("p"); this.minDiv=document.createElement("p"); this.maxDiv=document.createElement("p"); this.dragDiv=document.createElement("p"); Object.assign(p.style,{ position:"relative", }); this.minDiv.appendChild(this.dragDiv); p.appendChild(this.minDiv); p.appendChild(this.maxDiv); this.dragDiv.addEventListener(Drag.ELEM_MOVE_EVENT,this.moveHandler.bind(this)); Drag.dragElem(this.dragDiv,null,this.minDiv); this.minDiv.style.float=this.maxDiv.style.float="left"; return p; } set width(value){ this._width=value; this.render(); } get width(){ if(!this._width) this._width=0; return this._width; } set height(value){ this._height=value; this.render(); } get height(){ if(!this._height) this._height=0; return this._height; } set imgSource(value){ if(!Array.isArray(value))return; this._imgSource=value; LoadMethod.init(value); } set left(value){ this.zoomView.style.left=value+"px"; } set top(value){ this.zoomView.style.top=value+"px"; } loadFinishHandler(e){ this.targetList=e.targetList; this.width=this.width || e.targetList["min"].width; this.height=this.height || e.targetList["min"].height; } moveHandler(e){ if(!this.targetList || this.targetList.length<2) return; let widthScale=this.targetList["min"].width/this.targetList["max"].width; let heightScale=this.targetList["min"].height/this.targetList["max"].height; Object.assign(this.maxDiv.style,{ backgroundPositionX:-e.point.x/widthScale+"px", backgroundPositionY:-e.point.y/widthScale+"px", }); } render(){ if(!this.targetList || this.targetList.length<2) return; Object.assign(this.minDiv.style,{ width:this.width+"px", height:this.height+"px", border:"1px solid #000000", backgroundImage:`url(${this.targetList["min"].src})`, position:"relative" }); Object.assign(this.maxDiv.style,{ width:this.width+"px", height:this.height+"px", backgroundImage:`url(${this.targetList["max"].src})`, position:"relative" }); let widthScale=this.targetList["min"].width/this.targetList["max"].width; let heightScale=this.targetList["min"].height/this.targetList["max"].height; Object.assign(this.dragDiv.style,{ width:this.width*widthScale+"px", height:this.height*heightScale+"px", backgroundColor:"rgba(255,0,0,0.2)", position:"absolute" }) }}
html:
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Title</title> <script src="js/LoadMethod.js"></script> <script src="js/ZoomClasses.js"></script></head><body> <script> let zoom=new ZoomClasses(document.body); zoom.imgSource=["img/max.jpg","img/min.jpg"]; </script></body></html>
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