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How to solve some simple calculation problems with JS

小云云Original: 2018-02-26 09:06:401595browse

The function of js is very powerful. This article mainly shares with you how JS solves some simple calculation problems. I hope it can help everyone.

Let’s first take a look at the effect after running:

Next we will share with you all the code:

<!doctype html>  
<html>  
  <head>  
  <meta charset="utf-8">  
  <title>document</title>  
  <style type="text/css">  
/*计算器的style*/  
.jisuanqi {  
  width: 270px;  
  height: 200px;  
  border: 1px solid black;  
  list-style-type: none;  
  background: #C9E495;  
  margin: 10px 0px 10px 0px;  
}  
.jisuanqi span {  
  width: 20px;  
  height: 10px;  
  margin-right: 5px;  
}  
.jisuanqi input {  
  margin-bottom: 5px;  
}  
[name=yunsuanfu] {  
  width: 50px;  
  height: 30px;  
  margin-left: 10px;  
}  
/*一元二次函数求根style*/  
.box {  
  width: 300px;  
  height: 200px;  
  border: 1px solid black;  
  text-align: center;  
  background: #C9E495;  
}  
.box input {  
  margin-bottom: 10px;  
}  
</style>  
  <script type="text/javascript">  
  //计算10-100之和  
  function Sum(){  
    var i=0;  
    for (var j=10;j<=100;j++){  
      i+=j;  
    }  
    document.getElementById("count").value=i;  
  }  
  //判断是否闰年  
  function Runnian() {   
    var year = document.getElementById("year").value;   
    if (year==""){  
      alert("请先输入年份");  
    }  
    else if (year<=0){  
      alert("请输入大于0的年份");  
    }  
    else if ((year % 4 == 0) && (year % 100 != 0 || year % 400 == 0)){  
      document.write(year+"是闰年"+"\n");  
      document.write("<a href=&#39;&#39;>返回重新输入</a>")  
    }  
    else{    
      document.write(year+"不是闰年"+"\n");   
      document.write("<a href=&#39;&#39;>返回重新输入</a>")  
    }   
  }   
  //计算器1  
  function Calculate (){  
    var sum=0;  
    var num1 = parseFloat(document.getElementById("text1").value);  
    var num2 = parseFloat(document.getElementById("text2").value);  
    var sel = document.getElementById("select").value;  
    switch(sel){  
      case "+":sum=num1+num2;break;  
      case "-":sum=num1-num2;break;  
      case "*":sum=num1*num2;break;  
      case "/":sum=num1/num2;break;  
      default:sum="请输入数字选择运算符";break;  
      }  
      document.getElementById("jieguo").value = sum;  
  }  
    //计算器2  
    function Cal(count){      
      var sum;  
      var num1 = parseFloat(document.getElementById("text3").value);  
      var num2 = parseFloat(document.getElementById("text4").value);  
      switch(count){  
        case "+":sum=num1+num2;break;  
        case "-":sum=num1-num2;break;  
        case "*":sum=num1*num2;break;  
        case "/":sum=num1/num2;break;  
      }  
        document.getElementById("result").value = (sum.toFixed(2));  
    }  
    //计算一元二次函数根  
    function hanshu(){  
    var a=parseFloat(document.getElementById("txta").value);  
    var b=parseFloat(document.getElementById("txtb").value);  
    var c=parseFloat(document.getElementById("txtc").value);  
    var d=b*b-4*a*c  
    var r1=(-b+Math.sqrt(d))/(2*a);  
    var r2=(-b-Math.sqrt(d))/(2*a);  
    document.getElementById("txt1").value=(r1.toFixed(2));  
    document.getElementById("txt2").value=(r2.toFixed(2));  
    }  
  </script>  
  </head>  
  <body>  
<!--第1题计算10到100之和-->  
<input type="button" value="计算" onClick="Sum()" >  
<input type="text" id="count" value="单击计算10-100之和">  
<!--第2题判断是否为闰年-->  
<p></p>  
<p>判断是否为闰年：</p>  
<input type="search" id="year" maxlength="4">  
<input type="button" value="计算" onClick="Runnian()">  
<!--第三题计算器-->  
<p></p>  
<input type="text" id="text1" size="5">  
<select id="select">  
   <option value="">选择运算符</option>  
   <option value="+">+</option>  
   <option value="-">-</option>  
   <option value="*">*</option>  
   <option value="/">/</option>  
  </select>  
<input type="text" id="text2" size="5">  
<input type="button" value=" = " onClick = "Calculate()">  
<input type="text" id="jieguo">  
<!--计算器-->  
<p class="jisuanqi">  
   <h2>购物简易计算器</h2>  
   <li><span>第一个数</span>  
  <input type="search" id="text3">  
 </li>  
   <li><span>第二个数</span>  
  <input type="search" id="text4">  
 </li>  
   <li>  
  <input type="button" value=" + " name="yunsuanfu" onClick="Cal(&#39;+&#39;)">  
  <input type="button" value=" - " name="yunsuanfu" onClick="Cal(&#39;-&#39;)">  
  <input type="button" value=" × " name="yunsuanfu" onClick="Cal(&#39;*&#39;)">  
  <input type="button" value=" ÷ " name="yunsuanfu" onClick="Cal(&#39;/&#39;)">  
 </li>  
   <li><span>计算结果</span>  
  <input type="search" id="result">  
 </li>  
  </p>  
<p class="box">  
   <h3>分别输入abc求根</h3>  
   <input type="text" size="3" value="" id="txta">  
   <input type="text" size="3" value="" id="txtb">  
   <input type="text" size="3" value="" id="txtc">  
   <br />  
   <input type="button" value="求根" onClick="hanshu()">  
   <br />  
   <input type="text" size="7" id="txt1">  
   <input type="text" size="7" id="txt2">  
  </p>  
</body>  
</html>

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