本文实例为大家分享了js实现自定义滚动条组件的具体代码,供大家参考,具体内容如下
功能需求:
1、按照数据结构创建菜单内容,显示在页面中;
2、点击菜单后,显示对应的下级菜单内容,如果整体内容溢出,则出现滚动条;
3、滚动条的高度要随着整体内容高度的改变而改变。
4、鼠标拖动滚动条,整体内容要随着向上滚动。
5、当鼠标滚动时,滚动条和整体内容也要相应滚动。
来看一下效果:
默认状态:
点击菜单,内容溢出后,出现滚动条;
鼠标拖动滚动条,整体内容随着向上滚动:
分析:
- 这个案例中包括折叠菜单和滚动条两个组件 ,所以可以分开来写,然后整合到一起。
- 折叠菜单中要考虑多级菜单出现的情况,使用递归来做,数据的结构一定要统一,方便对数据进行处理。
- 滚动条的创建中,有两个比例等式,一是滚动条的高度/外层div高度=外层div高度/整体内容高度;二是滚动条的位置/(外层div高度-滚动条高度)=内容的scrollTop/(整体内容的高度-外层div高度)
- 当点击折叠菜单后,需要相应地设置滚动条的高度。折叠菜单是在Menu.js文件中,滚动条的设置是在ScrollBar.js文件中,需要进行抛发、监听事件。
- 监听菜单鼠标滚动的事件,当鼠标滚动时,判断滚轮方向,设置滚动条和内容的 top 值,也需要用到事件的抛发和监听。
下面附上代码:
html结构,模拟数据,创建外层容器:
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<!DOCTYPE html> < html lang = "en" > < head > < meta charset = "UTF-8" > < meta name = "viewport" content = "width=device-width, initial-scale=1.0" > < title >scrollBar</ title > </ head > < body > < script type = "module" > import Utils from './js/Utils.js'; import Menu from './js/Menu.js'; import ScrollBar from './js/ScrollBar.js'; var arr=[ {name:"A",category:[ {name:"奥迪",category:[ {name:"奥迪A3",href:""}, {name:"奥迪A4L",category:[ {name:"奥迪A4L-1",href:""} ]}, {name:"奥迪Q3",href:""}, {name:"奥迪Q5L",href:""}, {name:"奥迪Q2L",href:""}, {name:"奥迪Q7(进口)",href:""}, {name:"奥迪Q8(进口)",href:""}, {name:"奥迪Q7新能源",href:""}, ]}, {name:"阿尔法-罗密欧",category:[ {name:"Stelvio(进口)",href:""}, {name:"Giulia(进口)",href:""}, ]} ]}, {name:"B",category:[ {name:"奔驰",category:[ {name:"奔驰C级",href:""}, {name:"奔驰E级",href:""}, {name:"奔驰GLA级",href:""}, {name:"奔驰GLC级",href:""}, {name:"奔驰A级",href:""}, {name:"奔驰E级(进口)",href:""}, {name:"奔驰A级(进口)",href:""}, {name:"奔驰B级(进口)",href:""}, {name:"威霆",href:""}, {name:"奔驰V级",href:""}, ]}, {name:"宝马",category:[ {name:"宝马5系",href:""}, {name:"宝马1系",href:""}, {name:"宝马X1",href:""}, {name:"宝马X5(进口)",href:""}, {name:"宝马X6(进口)",href:""}, ]}, {name:"本田",category:[ {name:"竞瑞",href:""}, {name:"思域",href:""}, {name:"本田CR-V",href:""}, {name:"本田XR-V",href:""}, {name:"本田UR-V",href:""}, {name:"艾力绅",href:""}, {name:"享域",href:""}, {name:"INSPIRE",href:""}, {name:"凌派",href:""}, {name:"雅阁",href:""}, {name:"缤智",href:""}, ]}, {name:"别克",category:[ {name:"凯越",href:""}, {name:"英朗",href:""}, {name:"威朗",href:""}, {name:"阅朗",href:""}, {name:"君威",href:""}, {name:"君越",href:""}, {name:"昂科拉",href:""}, {name:"昂科威",href:""}, {name:"别克GL8",href:""}, {name:"别克GL6",href:""}, {name:"VELITE",href:""}, ]} ]} ] var container; init(); function init(){ createMenu(arr); createScrollBar(); } function createMenu(arr){ //创建菜单 let menu=new Menu(arr); //创建最外层容器 container=Utils.createE("div",{ width:"235px", height:"360px", border:"1px solid #ccc", position:"relative", overflow:"hidden" }) menu.appendTo(container); Utils.appendTo(container,"body") } function createScrollBar(){ //创建滚动条 let scrollBar=new ScrollBar(container); scrollBar.appendTo(container); } </ script > </ body > </ html > |
Menu.js文件,根据数据创建折叠菜单内容:
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import Utils from './Utils.js' ; export default class Menu{ static SET_BAR_HEIGHT= "set_bar_height" ; static MOUSE_WHEEL_EVENT= "mouse_wheel_event" ; constructor(_list){ this .elem= this .createElem(_list); } createElem(_list){ if ( this .elem) return this .elem; //创建最外层ul容器 let ul=Utils.createE( "ul" ,{ listStyle: "none" , padding: "0px" , margin: "0px" , width: "235px" , height: "360px" , color: "#333" , fontSize: "14px" , userSelect: "none" , position: "absolute" }); //创建li列表 this .createMenu(_list,ul); //ul监听点击事件 ul.addEventListener( "click" ,e=> this .clickHandler(e)); //ul监听滚轮事件,火狐使用DOMMouseScroll,其它浏览器使用mousewheel ul.addEventListener( "mousewheel" ,e=> this .mouseWheelHandler(e)); ul.addEventListener( "DOMMouseScroll" ,e=> this .mouseWheelHandler(e)); return ul; } appendTo(parent){ Utils.appendTo( this .elem,parent); } //创建一级菜单 createMenu(_list,parent){ for (let i=0;i<_list.length;i++){ let li=Utils.createE( "li" ,{ background: "#f5f5f5" , borderTop: "1px solid #ddd" , lineHeight: "32px" , },{ data:1, //控制一级菜单不能点击折叠 }) let span=Utils.createE( "span" ,{ marginLeft: "14px" , fontSize: "18px" },{ textContent:_list[i].name }) Utils.appendTo(span,li); Utils.appendTo(li,parent); //创建子菜单,第三个参数控制子菜单是否显示 this .createSubMenu(_list[i].category,li,0); } } //创建子菜单 createSubMenu(_subList,_parent,_index){ //如果没有子菜单,则跳出 if (_subList.length===0) return ; let subUl=Utils.createE( "ul" ,{ listStyle: "none" , background: "#fff" , padding: "0px" , margin: "0px" , fontSize: "14px" , display:_index===0? "block" : "none" }) for (let i=0;i<_subList.length;i++){ let subLi=Utils.createE( "li" ,{ paddingLeft: "40px" , position: "relative" , cursor: "pointer" }) if (!_subList[i].category){ //如果当前菜单没有子菜单,则创建a标签,进行跳转 let subA=Utils.createE( "a" ,{ color: "#333" , textDecoration: "none" , width: "100%" , display: "inline-block" },{ textContent:_subList[i].name, href:_subList[i].href || "javascript:void(0)" , target:_subList[i].href ? "_blank" : "_self" }) Utils.appendTo(subA,subLi); } else { //如果当前菜单有子菜单,创建span标签 let subSpan=Utils.createE( "span" ,{ position: "absolute" , left: "20px" , top: "8px" , border: "1px solid #ccc" , display: "inline-block" , width: "10px" , height: "10px" , lineHeight: "8px" },{ textContent:_subList[i].category.length>0? "+" : "-" }) subLi.textContent=_subList[i].name; Utils.appendTo(subSpan,subLi); } Utils.appendTo(subLi,subUl); //如果当前菜单没有子菜单,则跳过下面的执行 if (!_subList[i].category) continue ; //将当前菜单的子菜单作为参数,进行递归 this .createSubMenu(_subList[i].category,subLi,1); } Utils.appendTo(subUl,_parent); } clickHandler(e){ //如果当前点击的不是li标签或者span,直接跳出 if (e.target.nodeName!== "LI" && e.target.nodeName!== "SPAN" ) return ; let targ; if (e.target.nodeName=== "SPAN" ) targ=e.target.parentElement; else targ=e.target; //如果当前点击Li下面没有子菜单,直接跳出 if (targ.children.length<=1) return ; //如果当前点击的是一级菜单,直接跳出 if (targ.data===1) return ; //控制当前点击的Li下的ul显示隐藏 if (!targ.bool) targ.lastElementChild.style.display= "block" ; else targ.lastElementChild.style.display= "none" ; targ.bool=!targ.bool; //改变span标签的内容 this .changeSpan(targ); //抛发事件,改变滚动条的高度 var evt= new Event(Menu.SET_BAR_HEIGHT); document.dispatchEvent(evt) } changeSpan(elem){ if (elem.lastElementChild.style.display=== "block" ){ elem.firstElementChild.textContent= "-" ; } else { elem.firstElementChild.textContent= "+" ; } } mouseWheelHandler(e){ //阻止事件冒泡 e.stopPropagation(); //火狐浏览器判断e.detail,e.detail<0时,表示滚轮往下,页面往上 let tag=e.detail,wheelDir; //其他浏览器判断e.deltaY,e.deltaY<0时,表示滚轮往下,页面往上 if (tag===0) tag=e.deltaY; if (tag>0){ //滚轮往下滚动,页面往上走 wheelDir= "down" ; } else { wheelDir= "up" ; } //抛发事件,将滚轮方向传递过去 let evt= new Event(Menu.MOUSE_WHEEL_EVENT); evt.wheelDirection=wheelDir; this .elem.dispatchEvent(evt); } } |
ScrollBar.js文件,创建滚动条,对滚动条进行操作:
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import Utils from './Utils.js' ; import Menu from './Menu.js' ; export default class ScrollBar { bar; conHeight; menuHeight; wheelSpeed=6; barTop=0; static SET_BAR_HEIGHT= "set_bar_height" ; constructor(parent) { this .container = parent; this .menuUl= this .container.firstElementChild; this .elem = this .createElem(); //侦听菜单的点击事件,动态改变滚动条的高度 document.addEventListener(ScrollBar.SET_BAR_HEIGHT,()=> this .setBarHeight()); //ul菜单侦听滚轮事件 this .menuUl.addEventListener(Menu.MOUSE_WHEEL_EVENT,e=> this .mouseWheelHandler(e)); } createElem() { if ( this .elem) return this .elem; //创建滚动条的外层容器 let div = Utils.createE( "div" , { width: "8px" , height: "100%" , position: "absolute" , right: "0px" , top: "0px" , }) this .createBar(div); return div; } appendTo(parent) { Utils.appendTo( this .elem,parent); } createBar(_parent) { if ( this .bar) return this .bar; //创建滚动条 this .bar = Utils.createE( "div" , { width: "100%" , position: "absolute" , left: "0px" , top: "0px" , borderRadius: "10px" , backgroundColor: "rgba(255,0,0,.5)" }) //设置滚动条hover状态的样式 this .bar.addEventListener( "mouseenter" ,e=> this .setMouseStateHandler(e)); this .bar.addEventListener( "mouseleave" ,e=> this .setMouseStateHandler(e)); //设置滚动条的高度 this .setBarHeight(); //侦听鼠标拖动事件 this .mouseHand = e => this .mouseHandler(e); this .bar.addEventListener( "mousedown" , this .mouseHand); Utils.appendTo( this .bar, _parent); } setBarHeight() { //外层父容器的高度 this .conHeight = this .container.clientHeight; //实际内容的高度 this .menuHeight = this .container.firstElementChild.scrollHeight; //如果实际内容的高度小于父容器的高度,滚动条隐藏 if ( this .conHeight >= this .menuHeight) this .bar.style.display = "none" ; else this .bar.style.display = "block" ; //计算滚动条的高度 let h = Math.floor( this .conHeight / this .menuHeight * this .conHeight); this .bar.style.height = h + "px" ; } setMouseStateHandler(e){ //设置滚动条hover状态的样式 if (e.type=== "mouseenter" ){ this .bar.style.backgroundColor= "rgba(255,0,0,1)" ; } else { this .bar.style.backgroundColor= "rgba(255,0,0,.5)" ; } } mouseHandler(e) { switch (e.type) { case "mousedown" : e.preventDefault(); this .y = e.offsetY; document.addEventListener( "mousemove" , this .mouseHand); document.addEventListener( "mouseup" , this .mouseHand); break ; case "mousemove" : //注意:getBoundingClientRect()返回的结果中,width height 都是包含border的 var rect = this .container.getBoundingClientRect(); this .barTop = e.clientY - rect.y - this .y; //滚动条移动 this .barMove(); break ; case "mouseup" : document.removeEventListener( "mousemove" , this .mouseHand); document.removeEventListener( "mouseup" , this .mouseHand); break ; } } mouseWheelHandler(e){ //滚轮事件 if (e.wheelDirection=== "down" ){ //滚动往下,菜单内容往上 this .barTop+= this .wheelSpeed; } else { this .barTop-= this .wheelSpeed; } //滚动条移动 this .barMove(); } barMove(){ if ( this .barTop < 0) this .barTop = 0; if ( this .barTop > this .conHeight - this .bar.offsetHeight) this .barTop = this .conHeight - this .bar.offsetHeight; this .bar.style.top = this .barTop + "px" ; //菜单内容滚动 this .menuMove(); } menuMove(){ //计算内容的滚动高度 let menuTop= this .barTop/( this .conHeight- this .bar.offsetHeight)*( this .menuHeight- this .conHeight); this .menuUl.style.top=-menuTop+ "px" ; } } |
Utils.js文件,是一个工具包:
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export default class Utils{ static createE(elem,style,prep){ elem=document.createElement(elem); if (style) for (let prop in style) elem.style[prop]=style[prop]; if (prep) for (let prop in prep) elem[prop]=prep[prop]; return elem; } static appendTo(elem,parent){ if (parent.constructor === String) parent = document.querySelector(parent); parent.appendChild(elem); } static randomNum(min,max){ return Math.floor(Math.random*(max-min)+min); } static randomColor(alpha){ alpha=alpha||Math.random().toFixed(1); if (isNaN(alpha)) alpha=1; if (alpha>1) alpha=1; if (alpha<0) alpha=0; let col= "rgba(" ; for (let i=0;i<3;i++){ col+=Utils.randomNum(0,256)+ "," ; } col+=alpha+ ")" ; return col; } static insertCss(select,styles){ if (document.styleSheets.length===0){ let styleS=Utils.createE( "style" ); Utils.appendTo(styleS,document.head); } let styleSheet=document.styleSheets[document.styleSheets.length-1]; let str=select+ "{" ; for ( var prop in styles){ str+=prop.replace(/[A-Z]/g, function (item){ return "-" +item.toLocaleLowerCase(); })+ ":" +styles[prop]+ ";" ; } str+= "}" styleSheet.insertRule(str,styleSheet.cssRules.length); } static getIdElem(elem,obj){ if (elem.id) obj[elem.id]=elem; if (elem.children.length===0) return obj; for (let i=0;i<elem.children.length;i++){ Utils.getIdElem(elem.children[i],obj); } } } |
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/charissa2017/article/details/104098404