8. Operators in Javascript

Operators

Operators are the special symbols that is used to perform some operation on oprends in an exporession

1. Airthmatic operator

   used for basic mathematical operations.

   Examples: + , - , , / , % , **

2. Assignment operators

   used to assign values to variables.

   Examples: = , += , -= , *= , /=

3. Comparison operators

   return true or false.

   Examples: == , === , !== , > , < , >= , <=

4. Logical operators

   Logical operators are used for boolean operations.

   Examples: && , || , !

5. Unary Operators

   Unary operators operate on a single operand.

   Examples: + , - , ++ , - -

6. Bitwise operators

   Bitwise operators perform operations on binary numbers.

   Examples: & , | , ^ , ~ , « , »

7. Conditional (Ternary ) Operator

   Shorthand for if-else.

   condition ? trueValue : falseValue;

8. Comma operator

   Allows multiple expressions to be evaluated in a single statement.

    let x = (1, 2, 3);
    console.log(x); // 3 (last expression is returned)
   

9. BigInt Operator

   BigInt (n suffix) is used for large numbers.

    let big = 9007199254740991n + 1n;
    console.log(big); // 9007199254740992n
   

10. String Operator

    The + operator is used for concatenation.

    let name = "Hello" + " World!";
    console.log(name); // "Hello World!"
    

Interview Questions

1. What will be the output?

    console.log("5" + 2); // 52
    console.log("5" - 2); //3
   
    console.log(null == undefined);  // true 
    console.log(null === undefined); // false
   

   • "5" + 2 → "52" (concatenation) Implicit(Type Coercion) type conversion in JS

   • "5" - 2 → 3 (numeric conversion)

2. What is the result of true + true?

   true is converted to 1, so 1 + 1 = 2.

3. What will be the output ?

     console.log(false ? "Truthy" : "Falsy"); // falsy 
    console.log("" ? "Truthy" : "Falsy"); // falsy 
    console.log(0 ? "Truthy" : "Falsy");// falsy
    console.log(-0 ? "Truthy" : "Falsy");// falsy 
    console.log(null ? "Truthy" : "Falsy");// falsy 
    console.log(NaN ? "Truthy" : "Falsy");// falsy 
    console.log(undefined ? "Truthy" : "Falsy");// falsy 
   
    console.log({} ? "Truthy" : "Falsy"); // Truthy
    console.log([] ? "Truthy" : "Falsy"); // Truthy
    console.log(a ? "Truthy" : "Falsy"); // Truthy
   

4.   let a = 1;
     let b = (a++, a); // comma operator 
     console.log(b);
   

   Output :

   2

   (a++, a) executes a++, but returns the last expression (a).

5.   console.log({} == {});  // false
     console.log([] == []);  // false
     console.log([] == ![]); // true
   

   Objects ({} or []) are compared by reference, not value.

Next Topic

Functions in javascript