console.log("Hello, World!"); //1. Create a variable `isHappy` and assign it a boolean value based on the value of the given String variable `action`, whether it is `Smile` or not. var action = "Smile" var isHappy=action ==="Smile"; console.log(isHappy); // 2. Create a variable `favoriteSubjects` and assign it an array of strings representing your favorite subjects. var favoriteSubjects=["English","Biology","Mathematics"]; console.log(favoriteSubjects); // 3. Write a program to compare two numbers, `num1` and `num2`, and check if `num1` is greater than or equal to `num2`. var num1 = 10; var num2 = 5; if(num1>=num2){ console.log("num1 is greater than or equal to num2"); } else{ console.log("num2 is greater than or equal to num1"); } // 4. Write a program to calculate the square of a given number, `num`. var num = 4; var square = num * num; console.log("The square of", num, "is", square); // 5. Write a program to check if a given number, `num`, is even or odd. var num = 7; if (num % 2 === 0){ console.log(num+"is even"); } else{ console.log(num+"is odd"); } // 6. Write a program to check if a given year, `year`, is a leap year and divisible by 400 or divisible by 4 but not divisible by 100. var year = 2024; if ((year % 400 === 0) || (year % 4 === 0 && year % 100 !== 0)) { console.log(year + " is a leap year"); } else { console.log(year + " is not a leap year"); } // 7. Write a program that checks if a given character, `char`, is a vowel or a consonant. var char = "a"; var char = "a"; // Convert the character to lowercase for case-insensitive comparison var lowercaseChar = char.toLowerCase(); if ( lowercaseChar === "a" || lowercaseChar === "e" || lowercaseChar === "i" || lowercaseChar === "o" || lowercaseChar === "u" ) { console.log(char + " is a vowel"); } else { console.log(char + " is a consonant"); } // 8. Write a program that determines the largest among three numbers, `num1`, `num2`, and `num3`. var num1 = 10; var num2 = 5; var num3 = 8; var largest; if( num1 >= num2 && num1 >= num3 ){ largest=num1; } else if ( num2 >= num1 && num2 >= num3 ){ largest=num2; } else { largest=num3; } console.log(largest); // 9. Write a program that determines the sign of a given number, `num` (positive, negative, or zero), using the ternary operator. var num = -5; var sign = (num > 0) ? "positive" : (num < 0) ? "negative" : "zero"; console.log("The number is",sign ); // 10. Write a program that determines the grade based on a given percentage, `percentage`. Use the following grading scale: A (90-100), B (80-89), C (70-79), D (60-69), F (0-59). var percentage = 85; var grade; if(percentage >= 90 && percentage <= 100){ grade = "A"; } else if (percentage >=80 && percentage <= 90) { grade="B"; } else if (percentage >=70 && percentage <= 80) { grade="c"; } else if (percentage >=60 && percentage <= 70) { grade="D"; } else{grade="F";} console.log("The grade for", percentage,"percentage is",grade);
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Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.
var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
terminal: false
});
rl.on('line', function(line){
console.log("Hello, " + line);
});
Keyword | Description | Scope |
---|---|---|
var | Var is used to declare variables(old way of declaring variables) | Function or global scope |
let | let is also used to declare variables(new way) | Global or block Scope |
const | const is used to declare const values. Once the value is assigned, it can not be modified | Global or block Scope |
let greetings = `Hello ${name}`
const msg = `
hello
world!
`
An array is a collection of items or values.
let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);
let mobiles = ["iPhone", "Samsung", "Pixel"];
// accessing an array
console.log(mobiles[0]);
// changing an array element
mobiles[3] = "Nokia";
Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.
() => expression
const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
.map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);
let [firstName, lastName] = ['Foo', 'Bar']
let {firstName, lastName} = {
firstName: 'Foo',
lastName: 'Bar'
}
const {
title,
firstName,
lastName,
...rest
} = record;
//Object spread
const post = {
...options,
type: "new"
}
//array spread
const users = [
...adminUsers,
...normalUsers
]
function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
console.log(`Hello ${name}!`);
}
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar
IF is used to execute a block of code based on a condition.
if(condition){
// code
}
Else part is used to execute the block of code when the condition fails.
if(condition){
// code
} else {
// code
}
Switch is used to replace nested If-Else statements.
switch(condition){
case 'value1' :
//code
[break;]
case 'value2' :
//code
[break;]
.......
default :
//code
[break;]
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while (condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.
class className {
constructor() { ... } //Mandatory Class method
method1() { ... }
method2() { ... }
...
}
class Mobile {
constructor(model) {
this.name = model;
}
}
mbl = new Mobile("iPhone");