wap-notes

JavaScript Notes: Comments, Operators, and Conditional Statements

1. Comments in JavaScript

• Single-line Comment:
  Use // to comment out a single line of code.

  // This is a single-line comment
  let x = 10;  // This is also a comment
  

• Multi-line Comment:
  Use /* ... */ to comment out multiple lines of code.

  /*
   This is a 
   multi-line comment
  */
  let y = 20;
  

2. Operators in JavaScript

Operators are symbols that perform operations on variables and values.

Types of Operators:

1. Arithmetic Operators:
   • Used for mathematical calculations.
   • Examples:

     let a = 10;
     let b = 5;
     
     console.log(a + b); // Addition: 15
     console.log(a - b); // Subtraction: 5
     console.log(a * b); // Multiplication: 50
     console.log(a / b); // Division: 2
     console.log(a % b); // Modulus: 0 (remainder)
     

2. Assignment Operators:
   • Used to assign values to variables.
   • Examples:

     let x = 10;  // Assign 10 to x
     x += 5;      // x = x + 5 (x becomes 15)
     x -= 2;      // x = x - 2 (x becomes 13)
     

3. Comparison Operators:
   • Used to compare two values.
   • Examples:

     let a = 10;
     let b = 20;
     
     console.log(a == b);  // Equal to: false
     console.log(a != b);  // Not equal to: true
     console.log(a > b);   // Greater than: false
     console.log(a < b);   // Less than: true
     

4. Logical Operators:
   • Used to combine two or more conditions.
   • Examples:

     let a = 10;
     let b = 20;
     
     console.log(a > 5 && b > 15);  // Logical AND: true
     console.log(a > 15 || b > 15); // Logical OR: true
     console.log(!(a > 15));        // Logical NOT: true
     

5. Increment/Decrement Operators:
   • Used to increase or decrease the value of a variable by 1.
   • Examples:

     let count = 5;
     count++;  // Increment: count becomes 6
     count--;  // Decrement: count becomes 5
     

6. Ternary Operator:
   • A shorthand for if-else statements.
   • Example:

     let age = 18;
     let result = (age >= 18) ? "Adult" : "Minor";
     console.log(result); // Output: "Adult"
     

3. Conditional Statements in JavaScript

Conditional statements are used to perform different actions based on different conditions.

1. if Statement:
   • Executes a block of code if the specified condition is true.
   • Example:

     let age = 18;
     if (age >= 18) {
         console.log("You are eligible to vote.");
     }
     

2. if-else Statement:
   • Executes one block of code if the condition is true, and another if it is false.
   • Example:

     let age = 16;
     if (age >= 18) {
         console.log("You are eligible to vote.");
     } else {
         console.log("You are not eligible to vote.");
     }
     

3. if-else if-else Statement:
   • Executes multiple blocks of code depending on different conditions.
   • Example:

     let marks = 85;
     
     if (marks >= 90) {
         console.log("Grade A");
     } else if (marks >= 75) {
         console.log("Grade B");
     } else if (marks >= 50) {
         console.log("Grade C");
     } else {
         console.log("Fail");
     }
     

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