本文实例为大家分享了制作javascript简易画板的方法，供大家参考，具体内容如下
html：
<body id="bodys"> <span id="eraser"> 清除所有 </span> <span id="colorbtn"> 笔画颜色 </span> <input type="range" name="ram" id="ram" min="1" max="20" step="1" value="10"/> <label id="ramnum">字体大小:10px</label> <ul id="colorpanel"> <li>黑色</li> <li>红色</li> <li>绿色</li> <li>蓝色</li> </ul> </body>
CSS：
*{ margin: 0; padding: 0; } .box_black{ background-color: black; position: absolute; } .box_red{ background-color: red; position: absolute; } .box_green{ background-color: green; position: absolute; } .box_blue{ background-color: blue; position: absolute; } #eraser{ width: 80px; height: 50px; background-color: brown; display: inline-block; text-align: center; line-height: 50px; cursor: pointer; } #colorbtn{ width: 80px; height: 50px; background-color: tomato; display: inline-block; text-align: center; line-height: 50px; cursor: pointer; } #colorpanel{ width: 80px; height: 200px; list-style: none; margin-left: 88px; display: none; } #colorpanel>li{ width: 80px; height: 50px; text-align: center; line-height: 50px; background-color: aquamarine; display: inline-block; cursor: pointer; } #colorpanel>li:hover{ background-color: orange; }
javascript：
window.onload=function(){ //把类名存成一个数组 var classname=["box_black","box_red","box_green","box_blue"]; //默认类名为box_black var clsname=classname[0]; var oBody=document.getElementById("bodys"); var oDiv=oBody.getElementsByTagName("div"); var eraser=document.getElementById("eraser"); var colorbtn=document.getElementById("colorbtn"); var colorpanel=document.getElementById("colorpanel"); var ram=document.getElementById("ram"); var ramnum=document.getElementById("ramnum"); colorbtn.onmouseover=function(){ colorpanel.style.display="block"; } colorbtn.onmouseout=function(){ colorpanel.style.display="none"; } colorpanel.onmouseover=function(){ this.style.display="block"; } colorpanel.onmouseout=function(){ this.style.display="none"; } for(var i=0;i<colorpanel.children.length;i++){ colorpanel.children[i].index=i; colorpanel.children[i].onclick=function(){ //鼠标点击li切换类名来改变样式 clsname=classname[this.index]; colorpanel.style.display="none"; } } //定义默认字体大小为10px var WIDTH="10px"; var HEIGHT="10px"; //通过滑动range来改变字体大小 ram.onmousemove=function(){ WIDTH=HEIGHT=ram.value+"px"; ramnum.innerHTML="字体大小:"+WIDTH; } //鼠标点击屏幕，通过滑动鼠标不停创建div属性节点，并且给它设置样式 document.onmousedown=function(){ document.onmousemove=function(event){ var oevent=event||window.event; var scrolltop=document.documentElement.scrollTop||document.body.scrollTop; var scrollleft=document.documentElement.scrollLeft||document.body.scrollLeft; var box=document.createElement("div"); box.className=clsname; box.style.width=WIDTH; box.style.height=HEIGHT; oBody.appendChild(box); box.style.left=scrollleft+oevent.clientX+"px"; box.style.top=scrolltop+oevent.clientY+"px"; } } //当鼠标按键松开，注销鼠标滑动事件 document.onmouseup=function(){ document.onmousemove=null; } //当橡皮差按钮被点击，遍历所有div并且把它们一一从父节点里面移除 eraser.onclick=function(){ var oDiv=oBody.getElementsByTagName("div"); for(var i=0;i<oDiv.length;i++){ oBody.removeChild(oDiv[i]); } } //以下为取消按钮的冒泡事件，因为我们点击按钮是不能绘制div的 eraser.onmousedown=function(event){ var ievent=event||window.event; ievent.cancelBubble=true; } colorbtn.onmousedown=function(event){ var ievent=event||window.event; ievent.cancelBubble=true; } colorpanel.onmousedown=function(event){ var ievent=event||window.event; ievent.cancelBubble=true; } ram.onmousedown=function(event){ var ievent=event||window.event; ievent.cancelBubble=true; } } }
这是基于javascript的事件基础写的，比较简易，其实还可以进一步进行优化。下面来看效果图。
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查字典教程网。