Skip to content

part-2

Directory actions

More options

Directory actions

More options

Latest commit

 

History

History

part-2

Folders and files

NameName
Last commit message
Last commit date

parent directory

..
main
main
 
 
practice
practice
 
 
README.md
README.md
 
 

README.md

console.log()

To write (log) something on the console

console.log("Hello World");

console.log(12345);

console.log(2 + 2);

console.log("Hello", "World", 123);

Linking JS File

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>Hello JavaScript!!</h1>
    <script src="app.js"></script> <!-- Linking JS File -->
</body>
</html>

Template Literals

Used to add embedded expressions in a string.

let a = 5;
let b = 10;
console.log(`Price is ${a + b} rupees`);
// console.log("Price is", a + b, "rupees");

Operators in JS

  • Arithmetic (+, -, *, /, %, **)
  • Unary (++, --)
  • Assignment (=, +=, -=, *=, /=, %=, etc)
  • Comparison
  • Logical

Comparison Operator

Comparison Operators used to compare 2 values

  • >
  • >=
  • <
  • <=
  • ==
  • !=
  • ==, != compares value, not type
  • ===, !== compares value & type

Logical Operators

Logical operators are used to combine boolean expressions.

  • && Logical AND
  • || Logical OR
  • ! Logical NOT
true && true // true
true && false // false
false && true // false
false && false // false

true || true // true
true || false // true
false || true // true
false || false // false

!true // false
!false // true

truthy and falsy

Everything in JS is true or false (in boolean context).

This doesn't mean their value itself is true or false, but they are treated as true or false if taken in boolean context.

Falsy values

false, 0, -0, 0n (bigint value), ""(empty string), null, undefined, NaN

Truthy values

Everything else

Conditional Statements

  • if
  • if-else
  • else-if
  • switch
  • Ternary Operator (? :)

if Statement

if (some condition) {
    // Do SOMETHING
}

if-else Statement

if (condition1) {
    // Do SOMETHING
} else {
    // Do SOMETHING ELSE
}

else-if Statement

if (condition1) {
    // Do SOMETHING
} else if (condition2) {
    // Do SOMETHING ELSE
}

Nested if-else Statement

Nesting is writing if-else inside if-else statements. It can have many levels

if (condition1) {
    if (condition2) {
        // Do SOMETHING
    } else {
        // Do SOMETHING ELSE
    }
} else {
    // Do SOMETHING ELSE
}

switch Statement

Used when we have some fixed values that we need to compare to.

let color = "yellow";

switch (color) {
    case "red" :
        console.log ("Stop");
        break;
    case "yellow" :
        console.log ("Slow Down");
        break;
    case "green" :
        console.log ("Go");
        break;
    default :
        console.log ("Broken Light");
}

Alerts & Prompts

  • Alerts displays an alert message on the page.

    alert("Something is wrong!");

  • prompt displays a dialog box that asks user for some input.

    prompt("Please enter name")