使用 JavaScript 检查数字是否为 Prime

素数是只能被 1 和自身整除的数。前几个素数是：2, 3, 5, 7, 11, 13, 17, ...
JavaScript 使用 DOM 模型检查输入的数字是否为素数，并在屏幕上显示其相应的警报消息。

例子：

Input : 4
Output : Not Prime

Input : 5
Output : Prime

示例 1：本示例使用 alert函数显示结果。

  

    
        Check a number is Prime or
        not using JavaScript
    
      
    
      
        // Function to check prime number
        function p() {
              
            var n, i, flag = true;
              
            // Getting the value form text
            // field using DOM
            n = document.myform.n.value;
            n = parseInt(n)
            for(i = 2; i <= n - 1; i++)
                if (n % i == 0) {
                    flag = false;
                    break;
                }
                  
                // Check and display alert message
            if (flag == true)
                alert(n + " is prime");
            else
                alert(n + " is not prime");
        }
    

  

    
        GeeksforGeeks
          
        check number is prime or not
          
        
          
        
            Enter the number:
            
              
            
              
            
            
        
    

  

输出：

• 核对号码前：
  
• 核对号码后：
  

示例 2：此示例检查给定数字是否为质数并在控制台上显示结果。

  

    
        Check a number is Prime or
        not using JavaScript
    
      
    
        body {
            border:2px solid black;
            width:400px;
            height:150px;
            text-align:center;
        }
        h1 {
            color:green;
        }
    
      
    
      
        // Function to check for prime number
        function checkPrime() {
              
            var n, i, flag = true;
              
            // Getting the value form the
            // text field using DOM
            n = document.myform.n.value;
            n = parseInt(n)
            for (i = 2; i <= n - 1; i++)
                if (n % i == 0) {
                    flag = false;
                    break;
                }
                  
            // Check and display output
            if (flag == true)
                console.log(n + " is prime");
            else
                console.log(n + " is not prime");
        }
    

  

        GeeksforGeeks
        check number is prime or not
      
        
            Enter the number:
            
            
            
        
    

  
                                

输出：

• 核对号码前：
  
• 核对号码后：