用JS写一个计算器（兼容手机端） - 走看看

先看成果：
1.PC端

2.

首先确立html,有哪些东西我们要知道。布局大概的样子在心里有个数

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0"><title>瑞雪的计算器</title>
    <link rel="stylesheet" href="css/index.css">
    <script src="js/index.js" charset="utf-8"></script>
  </head>
  <body>
    <header>
        <li>LRX</li>temmo
    </header>
    <div class="calculator_box">
      <!-- //显示屏 -->
      <div class="display" id="dispaly">

      </div>
      <!-- 功能条 -->
      <div class="function">
        <button type="button" name="button" onclick="empty()">清空</button>
        <button type="button" name="button" onclick="back()">撤回</button>
        <div class="music">

        </div>
      </div>
      <div class="content">
      <!-- 数字框 -->
      <div class="number_box">
        <table>
          <tr>
            <td onclick="calculator()">9</td>
            <td onclick="calculator()">8</td>
            <td onclick="calculator()">7</td>
          </tr>
          <tr>
            <td onclick="calculator()">6</td>
            <td onclick="calculator()">5</td>
            <td onclick="calculator()">4</td>
          </tr>
          <tr>
              <td onclick="calculator()">3</td>
              <td onclick="calculator()">2</td>
              <td onclick="calculator()">1</td>
          </tr>
          <tr>
            <td colspan="2" onclick="calculator()">0</td>
            <td onclick="calculator()">.</td>
          </tr>
        </table>
      </div>
      <!-- 加减框 -->
      <div class="calculator">
        <table>
          <tr>
            <td onclick="calculator()">+</td>
            <td onclick="calculator()">-</td>
          </tr>
          <tr>
            <td onclick="calculator()">*</td>
            <td onclick="calculator()">/</td>
          </tr>
        </table>
        <button type="button" name="button" id="r_out" onClick="resultscalcaulte()">=</button>
      </div>

    </div>

    </div>
    <footer><img src="img/cat4.png" alt=""></footer>
  </body>
</html>

不过现在样式还很乱，不适合继续写JS所以，我开始设计样式，先在纸上画一画大概的样子............
写CSS代码：

body{
  margin: 0;
  background:#d67f5e;
}
header{
  text-align: center;
  background: rgb(121, 118, 138);
  margin-bottom: 50px;
  height: 40px;
  line-height: 40px;
  color: #fff;
}

header li{
  text-align: center;
   10%;
  background: rgb(148, 75, 75);
  border-top-right-radius: 20px;
  border-bottom-right-radius: 20px;

}
header li:hover{
  position: relative;
  margin-top: -34px;
  transition: 0.5s;
}

table{
  text-align: center;
}
.calculator_box{
   450px;
  height: 420px;
  background: rgb(112, 124, 152);
  margin: 0 auto;
  padding: 15px 0;
  border: 7px double #b0b0b0;
  border-radius: 30px;
  background-image: linear-gradient(to bottom, #5b7896, #00587b 32%);
  box-shadow: 0 3px 33px 8px rgba(22, 6, 6, 0.4), inset 0 0 28px 3px #4d4952;

}
.display{
   90%;
  margin: 0 auto;
  height: 70px;
  background: rgb(204, 194, 192);
  border-radius: 8px;
  background-color: #3f3c3b;
  box-shadow: 0 0 0px 1px #252829;
  font-size: 40px;
  color:#ffffff;
  text-align: right;
  line-height: 70px;
  padding-right: 10px;
}
.function button{
  height: 30px;
   60px;
  margin: 6px;
  border-radius: 15px;
  background-color: #b58068;
  color: white;
  text-shadow: 0 0 18px #2f2402;
  box-shadow: 0 0 0px 1px #4d4c51;
}
.number_box,.calculator,.music{
  display: inline-block;
}
.content{
   90%;
  margin: 0 auto;
  position: relative;
}

.function{
  margin: 10px auto;
   90%;
  margin: 13 auto;
  position: relative;
}
.music{
  border-top: 2px double #3c94c0;
  border-bottom:2px double #3c94c0;
   250px;
  height: 5px;
  border-radius: 3px;
}
.number_box tr,.calculator tr{
   inherit;
}
.number_box td{
   98px;
  height: 60px;
  background: rgb(235, 232, 233);
  border-radius: 5px;
  box-shadow: inset 0 0 7px 3px #c9c8c8;
}
.number_box td:active{
    background:#6c6a6a;
    box-shadow: inset 0 0 0px 0px #c9c8c8;
    transition: 0.5s;
    color: #fff;
}
.calculator{
   88px;
  position: relative;
  top: -47px;
  text-align: center;
  font-size: x-large;
}

.calculator td{
   44px;
  height: 72px;
  border-radius: 3px;
  text-shadow: 0px 0px 10px #1f1f1f;
  background-color: rgb(185, 185, 185);
  box-shadow: inset 0 0 8px 2px #9a9a9a;
  color: #ffffff;
}
.calculator td:active{
  box-shadow: inset 0 0 0px 0px ;
  background-color:#9c1414;
  transition: 0.5s;
}
#r_out{
   86px;
  height: 100px;
  border-radius: 8px;
  margin-top: 2px;
  color: aliceblue;
  background-color: #b55f5f;
  text-shadow: 0 0 12px black;
  box-shadow: inset 0 0 20px 3px #876161;
}
#r_out:active{
  background-color:#55595e;
  box-shadow: inset 0 0 0px 0px;
  transition: 0.5s;
}
footer img{
   302px;
  height: 267px;
}
footer img:hover{
  margin-right: -150px;
  transition: 0.5s

}

@media only screen and (max- 500px) {

    .calculator_box{
       95%;
      height: 390px;
      margin: 0 auto;
    }
    .number_box td{
       70px;
      height: 57px;
    }
    .calculator{
      margin-top: -47px;
    }
    .calculator td{
       44px;
      height: 66px;
    }
    .music{
       165px;
    }
    .content {
       81%;
      margin: 0 auto;
      position: relative;
    }
    header li{
      border-radius: 0px;
      border-bottom-right-radius: 20px;
      border-bottom-left-radius: 20px;

    }
}

@media only screen and (max- 400px){
  .calculator_box{
     95%;
    height: 390px;
    margin: 0 auto;
  }
  .number_box td{
     57px;
    height: 57px;
  }
  .calculator{
    margin-top: -47px;
    margin-left: 3px;
  }
  .calculator td{
     44px;
    height: 66px;
  }
  .music{
     154px;
  }

}
@media only screen and (max- 360px){
  .content {
     89%;
  }
  .calculator_box{
     95%;
    height: 390px;
    margin: 0 auto;
  }
  .number_box td{
     64px;
    height: 57px;
  }
  .calculator{
    display: inline-block;
    margin-top: -47px;
    margin-left: 2px;
  }
  .calculator td{
     44px;
    height: 66px;
  }
  .music{
     154px;
  }
}

@media only screen and (max- 320px){
  .number_box td{
     53px;
    height: 57px;
  }

}

用了好些个媒体查询！手机端必须做好，因为计算器，手机用的比较多，所以响应式必须做好

最后就是JS代码啦~

window.onload = function() {
     FastClick.attach(document.body);
 }
var display;
var result="";
var calresults;
display=document.getElementById("dispaly");
function calculator(){
  result+=event.srcElement.innerText;
  // alert(result);
  dispaly.innerText=result;

}
function resultscalcaulte(){
  var display=document.getElementById("dispaly");
  calresults=eval(result);
  display.innerText=calresults;
}
function empty(){
  result="";
  dispaly.innerText=result;
}
function back(){
  if (result!="") {
    result=result.substring(0, result.length - 1);
    dispaly.innerText=result;
  }
}

然后就把计算器发给小伙伴们用吧！
不过在手机上按键会有延迟~正在解决ing