Javascript notes

(1). number 1 script source code

// console.log("html file is running")

// ternary operator

// let a = 4;

// (a>5)? console.log("hello") : console.log("no hello")

// no 1------------------------------------------------

// let age = prompt("enter a number")

// Number.parseInt(age);

// let age = 12;

// (age>10 && age<20)? console.log("Your age is between 10 and 20"): console.log("Your age is less than 10 or greater than 20")

//no 2-------Switch case-----------------------------

// let num = 7;

// switch (num) {

// case 1:

// console.log("this is 1")

// break;

// case 2:

// console.log("this is 2")

// break;

// case 3:

// console.log("this is 3")

// break;

// case 4:

// console.log("this is 4")

// break;

// default:

// console.log('wrong input')

// break;

// }

//no 3----------Dvisible by 2 and 3------------------------------------

// let number ;

// number = parseInt(prompt("Enter a number"));

// if(number%2==0 && number%3==0){

// console.log(`The number ${number} is divisible by both 2 and 3`);

// }

// else{

// console.log(`The number ${number} is not divisible by both 2 and 3`);

// }

//no 4----------Dvisible by 2 or 3------------------------------------

// let number ;

// number = parseInt(prompt("Enter a number"));

// if(number%2==0 || number%3==0){

// console.log(`The number ${number} is divisible by 2 or 3`);

// }

// else{

// console.log(`The number ${number} is not divisible by 2 or 3`);

// }

//no 5-------you can drive or not--------------------

// let number5 ;

// number5 = parseInt(prompt("Enter your age"));

// (number5>=18 && number5<60)? console.log("Yes, You can drive"):console.log("No, You can't drive");

(2). number 2 script source code

console.log("html file is running")

// ----------------the for...in loop-----------------------

// let obj = {

// name:"Nabin",

// age:34,

// mark:66,

// dob:"2057\/07\/06"

// }

// console.log(obj.name) this will print "Nabin"

// for(let key in obj){

// // console.log(key) //this will print only the key not value

// console.log(obj[key]) //this will now print the value

// }

// we can also use for in loops for string and array

// for(let key in arr){

// // console.log(key) //this will print only the key or iteration of value not value

// console.log(arr[key])

// }

// for(let key in string){

// //console.log(key) //this will print only the key or iteration of value not value

// console.log(string[key])

// }

// ----------------the for...of loop-----------------------

// for--of loop will work in iterable data like string and array---------

// let arr = [34,"hi",65,true,null,{name:"Nabin",age:34,mark:66,dob:"2057\/07\/06"}]

// let string ="Nabin Rimal"

// for(let key of arr){

// console.log(key) //this will print the value of array

// }

// for(let key of string){

// console.log(key) //this will print the value of string

// }

// for--of loop will not works in not iterable data like object

// for(let key of obj){

// // console.log(key) //this will print only the key not value {This will no execute}

// console.log(key)

// }

//-----------function-----------

// declaring fuunction

// function add(a,b,v){

// let sum = a+b+v;

// console.log(sum)

// }

// add(45,45,4)

//another way to declare function

// no1-----------

// let sum= (a,b,v) =>{

// return a+b+v;

// }

//console.log(sum(4,45,45)) //output

// let sum2= (a,b,v=45) =>{

// return a+b+v;

// }

// console.log(sum2(4,45)) //output

// let add = sum(45,45,4);

// console.log(sum(45,45,4)) //output

// no2-----------

// let addition= () =>

// console.log("hello")

// addition()

//---------no1 ------------------------------

// let obj = {

// name:"nabin",

// age:23,

// height:5.8

// }

// console.log(Object.keys(obj)) //returns the keys of object

// console.log( Object.keys(obj).length) //returns the no. of keys of object

// for(let i =0;i<Object.keys(obj).length;i++){

// // console.log(Object.keys(obj)[i]) //prints only keys

// // console.log(obj[Object.keys(obj)[i]]) //prints values

// }

//---------no2 ------------------------------

// using for--in

// for(let key in obj){

// console.log(obj[key])

// }

//---------no3 ------------------------------

// let num = parseInt(prompt("Enter a number"));

// let random = Math.round(Math.random()*100);

// console.log(random)

// let num

// while(num!=random){

// console.log("Try again")

// num = parseInt(prompt("Enter a number"));

// }

// console.log("Correct number")

//---------no4 ------------------------------

// const avg = (a,b,v,d,s) => {

// return a+b+v+d+s;

// }

// console.log(avg(4,6,65,6,65))

(3). number 3 script source code

console.log("html file is running well")

// template leterals

// let Name = "Bipin Rimal"

// let age = 15

// let cls = 9

// let weight = 52

// let persondetail = ["Bipin Rimal",15,9,52]

// console.log(`My name is ${persondetail[0]}. I am ${persondetail[1]} years old. I study in class ${persondetail[2]}. My weight is ${persondetail[3]}.`)

//Escape sequenec character------------------------------

// console.table("My name is bipin rimal. My Mother\'s name is . she said \" i am a good person \"")

// console.log('hello\th')

// console.log('hello\rh')

///------------------string properties and methods------------------

// let fname = "Nabin"

// let lname = "Rimal"

// let str = "hello I am nabin rimal"

//------------length of array---------------

// console.log(fname.length,lname.length)

//--------------uppercase----------

// console.log(fname.toUpperCase(),lname.toUpperCase())

//-------------lowercase-------

// console.log(fname.toLowerCase(),lname.toLowerCase())

//-------slice-------

// console.log(str.slice(3,9))

// console.log(str.slice(11,22))

//-----------replaces--------

//creates a new string named newstr

// let newstr = str.replace("nabin","prabin")

// console.log(newstr)

// console.log(str.replace("nabin","prabin"))

//-------------concat-----

// console.log(fname.concat(" ",lname))

//----------------------trim------------------

// let strings = " Hello I am nabin rimal"

// let tri = strings.trim()

// console.log(tri)

// ---------------question no 1--------------------

// console.log("Nabin\"".length)

// ---------------question no 2--------------------

// let strings2 = "I am nabin rimal"

// -----------includes-----

// console.log(strings2.includes("nabin")) //"nabin" is in the strings2 so prints true

// console.log(strings2.includes("hi")) //"hi" is not in the strings2 so prints false

// ---------ends with---------

// console.log(strings2.endsWith("Rimal")) //outputs false

// console.log(strings2.endsWith("rimal")) //outputs true

// ----------start with ------------

// console.log(strings2.startsWith("i")) //outputs false

// console.log(strings2.startsWith("I")) //outputs true

// ---------------question no 3--------------------

// let strings3 = "I am NABIN Rimal"

// console.log(strings3.toLowerCase())

// ---------------question no 4--------------------

// let strings4 = "Please give Rs 1000"

// let num =parseInt(strings4.slice(15,19))

// console.log(typeof num,`=>>Take your ${num} Rs`)

// ---------------question no 5--------------------

// you can not change existing string any more with re initialize

// let strings3 = "I am NABIN Rimal"

// strings3[5] = "P"

// strings3[6] = "R"

// strings3[7] = "A"

// strings3[8] = "B"

// strings3[9] = "I"

// strings3[10] = "N"

// console.log(strings3)

(4). number 4 script source code

console.log("html file is running well")

//--------length of array---------

let arr = ["nabin", 22, true, 5 == 2]

// console.log(arr)

// let lengthofarr = arr.length

// console.log(lengthofarr)

//------arrays are mutable.arrays can be change-----------

// arr[0]="Nabin"

// console.log(arr,arr[0],typeof arr) //type of arr is an object in JS

//--------------------- Array Methods ------------

//------- Method ----------tostring()------

//-----convert to string separated with comma----

// console.log(arr.toString())

//------- Method 2----------join()------

//-------joins elements of array using a separator----

// let uparrow = arr.join('^')

// let underscore = arr.join("_")

// console.log(uparrow)

// console.log(underscore)

// console.log(arr)

//------- Method 3----------pop()------

//---remove last element from the array---

// let popedvalue = arr.pop()

// console.log(popedvalue) //returns the poped value

// console.log(arr) //+++++++++it updates the array+++++++++++

//------- Method 4----------shift()------

//-----remove first element from the array

// let shifted_value = arr.shift()

// console.log(shifted_value) //returns the shifted value

// console.log(arr) //+++++++++it updates the array+++++++++++

//------- Method 5----------push()------

//----add the new element at the end

// let pushed = arr.push("Rimal",55)

// console.log(pushed) //return the length of that array after pushed

// console.log(arr) //+++++++++it updates the array+++++++++++

//------- Method 6----------unShift()------

//----add the new element at the begining

// let unshifted = arr.unshift("Hello")

// console.log(unshifted) //return the length of that array after unshifted

// console.log(arr) //+++++++++it updates the array+++++++++++

//----Method 7----delete (it is an operator like typeof not function)-------

//--------delete the element of a specific index----------

// delete arr[3]

// console.log(arr) //deleted value shows empty

//----Method 8----concat()-------

//------------It is used to join arrays---------------

let arr2 = [34, 3, 5, 55, 23, 31]

// let concated_array = arr.concat(arr2,"concat joins two arrays")

// console.log(concated_array)

//----Method 8----sort()-------

//----------sort an array alphabetically---------

// let sorted = arr2.sort()

// console.log(sorted) // output the sorted array

//sort function sort value alphabetically. start form 1 and 2, 3,4 so on ===like [78,55,6,5,46,8] to [46,5,55,6,78,8]

//------it also updates the array---

// console.log(arr2)

// ----------sorting the number right way-----

// let compare_array = (num1, num2) => {

// // return num1-num2; //accending order

// // return num2-num1; //decending order

// }

// console.log(arr2.sort(compare_array)) //sorts the array

//----Method 9----splice()-------

//it is used to add new items to array

// it's sentence is

//arr.splice(position to add,no of element to remove,elements to add)

// let spliced_array = arr2.splice(1, 5, 44,54,64,74,84)

// console.log(spliced_array,"these are removed elements") //returns removed elements

// console.log(arr2) //---------it also changes exsting array---------

//---------Method 9----slice()---------

//slice the array into pieces

//arr2.slice(no of index starts from , no of index ends on but without including it )

// let sliced1 = arr2.slice(2)

// let sliced2 = arr2.slice(2,4)

// console.log(arr2,sliced1,sliced2) //it returns the sliced array and doesn't change the array

//---------Method 10----reverese()---------

// let reversed_array = arr2.reverse() //it will reverse and updates the array

// console.log(reversed_array,arr2)

// ---------------------Looping through array---------------

let arr3 = [1, 2, 3, 4, 5];

// (1)-----------foreach loop ----------------------

// let sum = 0;

// let narr = arr3.forEach((v) => {

// return sum = v + sum; //calls function for each element of arr2 and execute the fuction logic

// })

// console.log(sum)

// (2)-----------for.....of loop ----------------------

///for of loop only runs with iterable data types like string,array

// for(let key of arr3){

// console.log(key)

// }

// (3)-----------for.....in loop ----------------------

// for(let key in arr3){

// console.log(arr3[key])

// }

// (4)-----------array from loop ----------------------

let str2 = "Nabin_Rimal"

// console.log(typeof str2)

// let strToarray = Array.from(str2)

// console.log(strToarray, typeof strToarray, str2) // it does not update existing string

// (5)----------- Map----------------------

// it runs as same as foreach

// let b = 0;

// arr2.map((element) => {

// console.log(arr2[b], element + element)

// b += 1;

// })

// it will creates an array or returns an array

// let maped = arr3.map((element) => {

// return element * element

// })

// console.log(maped, arr3)

// (6)----------- Reduce----------------------

// reduce the array to a single value

// let reduced = arr3.reduce((k, h) => {

// return (k + h)

// })

// console.log(reduced, arr3)\

// (7)----------- filter----------------------

//filter an array with a condition and creates new array

// let filter_array =arr3.filter((value) =>{

// return value<3

// })

// console.log(filter_array,arr3)

// ----------------question 1------------

// let userinput = parseInt(prompt("Enter a Number"))

let newarr = [1, 2, 3];

// newarr.push(userinput);

// console.log(newarr)

// ----------------question 2------------

// let userinput;

// console.log(typeof userinput)

// -------------while loop---------

// while(userinput!=0){

// userinput = parseInt(prompt("Enter a Number"))

// newarr.push(userinput);

// }

// -------do while loop---------

// do{

// userinput = parseInt(prompt("Enter a Number"))

// newarr.push(userinput);

// }while(userinput!=0)

// ------for loop---------

// for(;userinput!==0;){

// userinput = parseInt(prompt("Enter a Number"))

// newarr.push(userinput)

// }

// console.log(newarr)

// ----------------question 3------------

// let arr6 = [55,6,1,21,21,10,152,410,1,50,51,0,08584,0,20200]

// let filtered = arr6.filter((arr6_value) => {

// return arr6_value%10==0

// })

// console.log(filtered)

// ----------------question 4------------

// let arr7 =[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50]

// let square_array = arr7.map((value)=>{

// return value*value

// })

// console.log(square_array)

// ----------------question 5------------

// input = parseInt(prompt("Enter the nth Natural number"))

// let factorial;

// if(input==0){

// factorial=1;

// }

// else{

// let blank_arr =[];

// for(let i=1;i<=input;i++){

// blank_arr.push(i);

// }

// console.log(blank_arr)

// factorial = blank_arr.reduce((val1,val2)=>{

// return val1*val2

// })

// }

// console.log(`the factorial of ${input} is ${factorial}`)

(5). number 5 HTML source code