JavaScript 写计算器改进版

<html>
<head>
<style>
 .short{height:50px;width:55px;float:left;}
</style>
</head>
<body>
<script>
var xianshi="";
var shuzi="";
var huanchun="";

//如果连续输入数字，则累加其值
function num(a){
  var pingmu=document.getElementById("pingmu");
  xianshi+=a;
  pingmu.value=xianshi;
  shuzi+=a
}

//如果缓存和数字为空，则第一个输入不能是符号
function fum(b){
  if(shuzi==""&&huanchun=="")return;   
  huanchun+=shuzi+b;
  shuzi="";
  xianshi="";
}

//求出缓存值，并清空其他值
function sum(){
  huanchun+=shuzi;
  var pingmu=document.getElementById("pingmu");
  huanchun=eval(huanchun);
  pingmu.value=huanchun;
  shuzi=""
  xianshi=""
}

//将屏幕上的值添加-号后，保存到缓存或者数字当中
function sign(){
  var pingmu=document.getElementById("pingmu")
  var value=pingmu.value;
  value="(-("+value+"))"
  value=eval(value)
  pingmu.value=value;
  if(shuzi=="")huanchun=value;
  else{shuzi=value;}
}

//倒数
function reciprocal(){
  var pingmu=document.getElementById("pingmu")
  var value=pingmu.value;
  value="1/"+value
  value=eval(value);
  pingmu.value=value;
  if(shuzi=="")huanchun=value;
  else{shuzi=value;}
}

//开方
function nsqrt(){
  var pingmu=document.getElementById("pingmu")
  var value=pingmu.value;
  value=eval(value);
  value=Math.sqrt(value);
  pingmu.value=value;
  if(shuzi=="")huanchun=value;
  else{shuzi=value;}
}

//小数点
function spot(){
  var pingmu=document.getElementById("pingmu");
  if(shuzi==""||xianshi==""){shuzi="0";xianshi="0"}
  shuzi+=".";
  xianshi+=".";
  pingmu.value=xianshi;
}

//十进制
function ten(){
  var total=0,pows=0
  var pingmu=document.getElementById("pingmu");
  var value=pingmu.value;
  var arr=value.split("");
  arr=arr.reverse();
  for(i=0;i<arr.length;i++){
  arr[i]-=0;
  pows=Math.pow(2,i);
  total+=arr[i]*pows;
  }
  pingmu.value=total;
  jisuan="";xianshi="";
}

//二进制
function two(){
  var pingmu=document.getElementById("pingmu");
  var value=pingmu.value;
  value-=0;
  var arr=new Array();
  for(i=0;1;i++){
  if(value==0)break;
  arr[i]=value%2;
  value/=2;
  value=parseInt(value);
  }
  arr=arr.reverse();
  str=arr.join("");
  pingmu.value=str;
  xianshi="";jisuan="";
}

//清空
function cee(){
  shuzi="";
  xianshi="";
  document.getElementById('pingmu').value="";
}

//清除
function ccc(){
  shuzi="";
  huanchun="";
  xianshi="";
  document.getElementById('pingmu').value="";
}

//退符
function cbb(){
  shuzi=shuzi.substring(0,shuzi.length-1)
  xianshi=xianshi.substring(0,xianshi.length-1);
  pingmu.value=xianshi;
}

</script>

<input id="pingmu" style="height: 36px; width: 282px; text-align: right;" type="text" /><br /><br />

<button class="short" onclick="cbb()" value="c">&larr;</button>
<button class="short" onclick="cee()" value="c">CE</button>
<button class="short" onclick="ccc()" value="c">C</button>
<button class="short" onclick="ten()" value="x">dec</button>
<button class="short" onclick="two()" value="x">bin</button><br /><br /><br />

<button class="short" onclick="num(this.value)" value="7">7</button>
<button class="short" onclick="num(this.value)" value="8">8</button>
<button class="short" onclick="num(this.value)" value="9">9</button>
<button class="short" onclick="fum(this.value)" value="*">*</button>
<button class="short" onclick="fum(this.value)" value="/">/</button><br /><br /><br />

<button class="short" onclick="num(this.value)" value="4">4</button>
<button class="short" onclick="num(this.value)" value="5">5</button>
<button class="short" onclick="num(this.value)" value="6">6</button>
<button class="short" onclick="fum(this.value)" value="-">-</button>
<button class="short" onclick="fum(this.value)" value="%">%</button><br /><br /><br />

<button class="short" onclick="num(this.value)" value="1">1</button>
<button class="short" onclick="num(this.value)" value="2">2</button>
<button class="short" onclick="num(this.value)" value="3">3</button>
<button class="short" onclick="fum(this.value)" value="+">+</button>
<button class="short" onclick="sum()" value="=">=</button>
<br /><br /><br />

<button class="short" onclick="num(this.value)" value="0">0</button>
<button class="short" onclick="sign()" value="+/-">+/-</button>
<button class="short" onclick="spot()" value=".">.</button>
<button class="short" onclick="reciprocal()" value="1/x">1/x</button>
<button class="short" onclick="nsqrt()" value="sqrt">sqrt</button><br /><br /><br /></p>
</script>
</body>

.short { height: 50px; width: 55px; float: left }

←
CE
C
dec
bin

7
8
9
*
/

4
5
6
-
%

1
2
3
+
=

0
+/-
.
1/x
sqrt