JavaScript Program to Check for Null
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Overview
In JavaScript programming language, there is a primitive data type known as 'null', which represents the empty value inside a variable. Although there is one more data type known as 'undefined', it does not represents the null value. In this article, we will discuss different methods to check for Null in JavaScript
Introduction
Null is a primitive type present in JavaScript which indicates the absence of any object value. When the value of a variable or an object is null, it indicates that the object value is absent in the variable. So, Null is often used at these places where an object can be expected, but no object is relevant.
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JavaScript Program to Check for Null Using typeof()
In this approach, we will use the typeof() method to find the type of an object or variable. The typeof method will return a string named 'object' if the variable passed as the parameter is null. Here we will use the !variable because applying ! in front of a null object will make the object not null. So, the if condition will become true.
JavaScript Implementation
Output
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Explanation
- In the first step, we created a variable x and initialized it with a null value.
- Inside the if condition, we have used the typeof() method to check the data type of x.
- The condition will be true if the value of typeof(x) will return true and the value of !x is also true.
- Finally, we have printed the result
JavaScript Program to Check for Null Using Equality Operator
In this approach, we will use the equality operator '==' to check if the variable contains null or not. If the value of x is null, then the statement inside the If block will be printed.
JavaScript Implementation
Output
Explanation
- In the first step, we created a variable x and initialized it with a null value.
- Inside the if condition, we are simply checking the value of x is null or not by using the equality operator '=='
- The condition will be true if the value x is null
- Finally, we have printed the result
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JavaScript Program to Check for Null Using Strict Equality Operator
In this approach, we will use the strict equality operator '===' to check if the variable contains null or not. If the value of x is null, then the statement inside the If block will be printed.
JavaScript Implementation
Output
Explanation
- In the first step, we created a variable x and initialized it with a null value.
- Inside the if condition, we are simply checking the value of x is null or not by using the strict equality operator '==='
- The condition will be true if the value x is null
- Finally, we have printed the result
JavaScript Program to Check for Null Using the Object.is() Method
In this approach, we will use the Object.is() method to check the type of an object. The Object.is() method accepts two parameters as an argument, the first is the object name, and the second is the object type that we want to check for the object. The Object.is() will return true if the data type of the first parameter will be equal to the second parameter passed as an argument inside the Object.is() method.
JavaScript Implementation
Output
Explanation
- In the first step, we created a variable x and initialized it with a null value.
- Inside the if condition, we have used the Object.is() operator to check the data type of x
- The condition will be true if the data type of the first parameter will be equal to the second parameter passed as an argument inside the Object.is() method.
- Finally, we have printed the result
Conclusion
In this quick article, we have discussed how to check for null in JavaScript and we can extract the following conclusions.
- Null is a primitive type present in JavaScript which indicates the absence of any object value.
- A variable that has not been assigned a value is of type 'undefined'.
- Null is often used at places where an object can be expected, but no object is relevant.
- The typeof method will return a string named 'object' if the variable passed as the parameter is null.
- The Object.is() method will return true if the type of the passed object (type of the first parameter) is the same as the object type passed as parameter (second parameter).
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