Use JS to do calculation problems

This time I will bring you the precautions for using JS to do calculation problems. What are the precautions for using JS to do calculation problems? The following is a practical case, let’s take a look.

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

Next we will share with you all the code:

nbsp;html>  
  
    
  <meta>  
  <title>document</title>  
  <style>  
/*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>  
  //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")  
    }  
    else{    
      document.write(year+"不是闰年"+"\n");   
      document.write("<a href=&#39;&#39;>返回重新输入")  
    }   
  }   
  //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>  
    
    
<!--第1题计算10到100之和-->  
<input>  
<input>  
<!--第2题判断是否为闰年-->  
<p></p>  
<p>判断是否为闰年：</p>  
<input>  
<input>  
<!--第三题计算器-->  
<p></p>  
<input>  
<select>  
   <option>选择运算符</option>  
   <option>+</option>  
   <option>-</option>  
   <option>*</option>  
   <option>/</option>  
  </select>  
<input>  
<input>  
<input>  
<!--计算器-->  
<p>  
   </p><h2 id="购物简易计算器">购物简易计算器</h2>  
   

第一个数         

      

第二个数         

      

                        

      

计算结果         

       

      

分别输入abc求根

                        
            
                      

I believe you have seen it You have mastered the method in the case of this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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