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。