By Object.is() function
This function checks whether two objects’ values are equal or not. If they are the same the two object’s values are the same if both values are null.
Syntax:
Object.is( a, null )'
Example: In this example, we are using Object.is() function.
Javascript
let maybeNull = null // The following is equivalent to // maybeNull == null // or maybeNull == undefined: console.log(Object.is(maybeNull, undefined) || Object.is(maybeNull, null)) // Compare to the following: console.log(maybeNull == null) console.log(maybeNull == undefined) console.log(maybeNull === null) console.log(Object.is(maybeNull, null)) console.log(maybeNull === undefined) console.log(Object.is(maybeNull, undefined)) maybeNull = undefined console.log(maybeNull === undefined || maybeNull === null) console.log(maybeNull == null) console.log(maybeNull == undefined) console.log(maybeNull === null) console.log(Object.is(maybeNull, null)) console.log(maybeNull === undefined) console.log(Object.is(maybeNull, undefined)) |
Output
true true true true true false false true true true false false true true
How to check for null values in JavaScript ?
The null values show the non-appearance of any object value. It is usually set on purpose to indicate that a variable has been declared but not yet assigned any value. This contrasts null from the similar primitive value undefined, which is an unintentional absence of any object value. That is because a variable that has been declared but not assigned any value is undefined, not null.
Below are the approaches:
Table of Content
- By equality Operator (===)
- By Object.is() function
- By the typeof Operator
- Using Lodash _.isNull() Method
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