How to avoid inserting NULL values to a table with JavaScript?

In order to get rid of null values inserted into a table, you need to check the condition while entering the value.

The condition to check NULL must be as follows −

while( !( yourVariableName1==null || yourVariableName2==null ||
yourVariableName3==null…...N){
   // yourStatement1
   .
   .
   N
}

The above logic will never allow inserting the null values.

Now you can use for loop and insert value into the table without NULL. Following is the code −

Example

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initialscale=1.0">
<title>Document</title>
<link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/fontawesome/4.7.0/css/font-awesome.min.css">
</head>
<body>
<h2>Demo Of Inserting the value into the table</h2>
<p>This is demo on the javascript array</p>
<p id="demo"></p>
<script>
   var index = 0;
   var firstNameArray = new Array();
   var lastNameArray = new Array();
   var firstName = "";
   var lastName = "";
   while (!(firstName == null || lastName == null)) {
      firstName = prompt("Please Enter your First Name=");
      lastName = prompt("Please Enter your Last Name=");
      firstNameArray[index] = firstName;
      lastNameArray[index] = lastName;
      index++;
   }
   document.writeln("<table border='1' width='50%'>");
   document.writeln("<caption>DEMO TABLE IN JAVASCRIPT</caption>");
   document.writeln("<th>FirstName</th><th>LastName</th>");
   for (var startIndex in firstNameArray) {
      if (firstNameArray[startIndex] !== null &&
         lastNameArray[startIndex] !== null)
         document.writeln("<tr><td>" + firstNameArray[startIndex] +
         "</td><td>" + lastNameArray[startIndex] + "</td></tr>");
      }
      document.write("</table>");
</script>
</body>
</html>

To run the above program, save the file name “anyName.html(index.html)” and right click on the file. Select the option “Open with Live Server” in VS Code editor.