How to Check Null Value in JavaScript

You can check for null values in JavaScript.

Using null parameters in JavaScript allows programmers to define a variable without assigning a value to it. Null values are used in simple variables like integers and strings, and they are used for objects on a Web page. However, null values become troublesome for calculations or object manipulation. If you have a defined variable in your code, checking for null values prior to executing code limits the number of errors.

Instructions

1. Declare the variable. Type the following into your JavaScript code:

   var myVal = null;

   This allocates memory and defines the variable for use.

2. Evaluate whether the variable is null. In some instances, you may want to execute code if the value is null. Wrap your executable code with this statement:

   if (myVal== null) {

   }

   This statement provides a way to execute code only if myVal is null.

3. Evaluate whether a variable is not null. In other instances, you may want to run code when a value is not null. The "!" operator tells the compiler to run the statements if the result is false. In this statement, JavaScript runs statements if myVal is not null:

   if (!name) {

   }

References

• WebReference: JavaScript Null Value
• Dev Guru: Shedding Light on the JavaScript Special Values Null and Undefined

Resources

• Read this Article in Spanish