注：本人为初学者，欢迎各位大神指教
在线试一试
简单计算器实现效果：
HTML代码counter.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>计算器</title>
<link rel="stylesheet" type="text/css" href="css/counter.css" />
<script type="text/javascript" src="js/counter.js"></script>
</head>
<body>
<div class="counter">
<div class="counter_top" >
<form>
<input type="text" id="top" value="" />
</form>
</div>
<div class="counter_down">
<form>
<input type="button" class="CE" value="清屏" onclick="cl(this.value)" />
<input type="button" class="CE" value="退格" onclick="cl(this.value)"/>
<div class="down_right" id="cou">
<input type="button" class="cou" value="÷" onclick="eva(this.value)"/>
<input type="button" class="cou" value="×" onclick="eva(this.value)"/>
<input type="button" class="cou" value="-" onclick="eva(this.value)"/>
<input type="button" class="cou" value="+" onclick="eva(this.value)"/>
<input type="button" class="cou" value="=" onclick="eva(this.value)"/>
</div>
<div id="down_num" >
<input type="button" class="num" value="7" onclick="show(this.value)"/>
<input type="button" class="num" value="8" onclick="show(this.value)"/>
<input type="button" class="num" value="9" onclick="show(this.value)"/>
<input type="button" class="num" value="4" onclick="show(this.value)" />
<input type="button" class="num" value="5" onclick="show(this.value)" />
<input type="button" class="num" value="6" onclick="show(this.value)"/>
<input type="button" class="num" value="1" onclick="show(this.value)"/>
<input type="button" class="num" value="2" onclick="show(this.value)"/>
<input type="button" class="num" value="3" onclick="show(this.value)"/>
<input type="button" class="num" value="0" onclick="show(this.value)"/>
<input type="button" class="num" value="." onclick="show(this.value)"/>
<input type="button" class="num" value="+/-" onclick="eva(this.value)"/>
</div>
</form>
</div>
</div>
</body>
</html>
CSS代码counter.css
.counter{
background-color: #E0E0E0;
width: 440px;
height: 460px;
padding: 20px;
}
.counter .counter_top{
width: 440px;
height: 53px;
background-color: #fff;
}
.counter .counter_top input{
width: 440px;
height: 53px;
border: 0px;
}
.counter_down .CE{
width: 152.5px;
height: 45px;
margin: 15px 15px 0px 0px;
}
.counter_down .cou{
width: 95px;
height: 45px;
margin-bottom: 15px;
}
.down_right{
width: 95px;
float: right;
margin-top: 15px;
}
.counter_down .num{
width: 95px;
height: 45px;
margin: 15px 16px 0px 0px;
}
js代码counter.js
var a=0;
var b;
var c = 0;
function show(value) {
document.getElementById("top").value +=value;
}
function eva(value){
c=parseFloat(document.getElementById("top").value);
if (value=="=") {
if(b=="+"){
document.getElementById("top").value=(a+c);
}else if(b=="-"){
document.getElementById("top").value=(a-c);
}else if(b=="×"){
document.getElementById("top").value=(a*c);
}else if(b=="÷"){
if(c==0){
document.getElementById("top").value="分母不能为0";
}else{
document.getElementById("top").value=(a/c);
}
}
}else{
a=parseFloat(document.getElementById("top").value);
document.getElementById("top").value="";
b=value;
if(b=="+/-"){
a=-a;
document.getElementById("top").value=a;
}
}
}
function cl(value){
if(value=="清屏"){
document.getElementById("top").value="";
}else{ document.getElementById("top").value=document.getElementById("top").value.substring(0,(document.getElementById("top").value.length-1))
}
}