- What are the different data types present in JavaScript?
JavaScript has 7 primitive data types:
- Numbers are used to represent numbers.
- Strings are used to represent text.
- Booleans are used to represent true or false values.
- Null is used to represent a value that is not defined.
- Undefined is used to represent a value that has not been defined.
- Symbols are used to represent unique values.
- BigInts are used to represent large numbers.
In addition to primitive data types, JavaScript also has object and array data types.
- Explain Hoisting in JavaScript.
Hoisting is a JavaScript feature that causes all variable declarations and function declarations to be moved to the top of their scope, even if they are not actually defined until later in the code. This can be a bit confusing, but it is important to understand how hoisting works in order to write correct JavaScript code.
- Why do we use the word “debugger” in JavaScript?
The word “debugger” is used in JavaScript to stop the execution of the code and enter the debugger. The debugger is a tool that allows you to step through your code line by line, inspect variables, and set breakpoints. This can be very helpful for debugging JavaScript code.
- Difference between “ == “ and “ === “ operators.
The ” == ” operator is used for loose equality comparison, while the ” === ” operator is used for strict equality comparison. Loose equality comparison means that the two values being compared are only equal if they are of the same type and have the same value. Strict equality comparison means that the two values being compared must be of the same type and have the same value, and they must also be located in the same place in memory.
- Difference between var and let keyword in javascript.
The var keyword is used to declare variables that are global or local to the current function. The let keyword is used to declare variables that are local to the current block of code. The main difference between var and let is that variables declared with let are block-scoped, while variables declared with var are function-scoped. This means that variables declared with let can only be accessed within the block in which they are declared, while variables declared with var can be accessed from anywhere within the function in which they are declared.