What is the Difference Between null and undefined in JavaScript?

In JavaScript, null and undefined both represent the absence of a meaningful value, but they have different meanings and use cases:

• Null:
• Represents an intentional empty or non-existent value.
• Is assigned to a variable, indicating that the variable has no value.
• Is an object, and when assigned to a variable, it represents no value.
• null is not strictly equal to undefined (null !== undefined), but they are loosely equal (null == undefined).
• Undefined:
• Represents the value of a variable that has not yet been initialized or assigned.
• Indicates that the variable does not exist in the compiler.
• Is a global object.
• Can be used to differentiate between null and undefined using isNaN().

Some key differences between null and undefined include:

1. null is an assigned value, indicating that the variable has no value, while undefined represents a variable that has not yet been assigned a value.
2. null is an object, whereas undefined is a global object.
3. When performing arithmetic operations, null is converted to 0, while undefined is converted to NaN.

In summary, null is used to represent an intentional empty value, while undefined represents a variable that has not yet been assigned a value. It is essential to understand the difference between null and undefined to write efficient and error-free JavaScript code.

Comparative Table: null vs undefined in JavaScript

The main difference between null and undefined in JavaScript is:

• null implies that the property exists but does not have a value.
• undefined implies that the property itself does not exist.

Here is a table summarizing the differences between null and undefined in JavaScript:

In most practical cases, both null and undefined denote empty values and carry no information.