1. What is the difference between
Understanding the difference between
null is a value that represents the intentional absence of any object value. On the other hand,
undefined indicates the absence of any assigned value to a variable.
null is explicitly assigned to a variable, while
undefined indicates that the variable has not been assigned a value.
4. What is the difference between
== operator compares values for equality, while the
=== operator compares both the value and the type of the values. The
== operator performs type coercion, which means that it converts the types of the values before comparison. The
=== operator does not perform type coercion, which makes it more strict and less prone to errors.
5. What is the
this keyword is a reference to the object that the function belongs to. It is determined by how the function is called, and it can change depending on the context. In the global scope,
this refers to the global object, which is usually the window object in a web browser. In a function,
this refers to the object that the function belongs to. In an event handler,
this refers to the element that triggered the event.
Can I use
undefined as a variable value?
undefined can be assigned to a variable, and it indicates that the variable has not been assigned a value.
Closures allow for data encapsulation and can be used to create private variables and functions. They also enable the creation of factory functions.
What is the purpose of the event loop?
Which operator is more strict,
== is called the equality operator and it checks if the values of two operands are equal. However, == does not check for the datatype of operands. On the other hand, === is called the strict equality operator and it checks if the values and datatypes of two operands are equal. The === operator will only return true if the values being compared are of the same datatype as well as have the same value.
What is the role of the
this keyword is a reference to the object that the function belongs to, and its value is determined by how the function is called.
What is the difference between
var declares a variable with function scope,
let declares a variable with block scope, and
const declares a constant variable with block scope.
By understanding the answers to these frequently asked questions, you will have a more in-depth understanding of the concepts covered in the article. Make sure to prepare for these questions before your next job interview.
undefined, the purpose of closures, the event loop, the
=== operators, and the