Completes content

Author: Prakhar0013

03_basics/03_arrow.js

@@ -27,11 +27,11 @@ const user= {
 //We are not able to get the context within a function
 //like using this within didn't return an object, instead, we get global value, performace evaluations etc
 
-// const chai(){
-//     let username="Prakhar"
-//     console.log(this.username);
-// }
-// chai()
+const chai=function(){
+    let username="Prakhar"
+    console.log(this.username);
+}
+chai()
 //Output: Here the output we get is actually undefined
 
 

05_iterations/eight.js

@@ -0,0 +1,30 @@
+const myNums= [1,2,3]
+
+// const myTotal= myNums.reduce(function(acc, currval) {
+//     console.log(`acc: ${acc} and currval: ${currval}`);
+//     return acc+currval},0)
+
+const myTotal = myNums.reduce((acc, curr)=>acc+curr,0)
+
+// console.log(myTotal);
+
+const shoppingCart=[
+    {
+        itemName: "JS Course",
+        price: 2999
+    },
+    {
+        itemName: "Python Course",
+        price: 2999
+    },
+    {
+        itemName: "Java Course",
+        price: 4999
+    },
+    {
+        itemName: "Data Science Course",
+        price: 7999
+    },
+]
+const priceToPay=shoppingCart.reduce((acc,item)=>acc+item.price,0)
+console.log(priceToPay);

05_iterations/five.js

@@ -0,0 +1,41 @@
+const coding = ["js", "ruby", "java", "python", "cpp"]
+
+//foreach
+//In for each loop we are creating a callback. A callback doesn't have a name
+//As a parameter, we take val(can take anything), for iterating through values in coding
+// coding.forEach( function (val) {
+//     console.log(val);
+// })
+
+//As a callback, we can use arrpw functions as well
+// coding.forEach( (item) => {console.log(item);
+// } )
+
+function printMe(item){
+    console.log(item);
+}
+// coding.forEach(printMe)
+//Note: Here, we giving reference of the function printMe, we are not executing it
+
+// coding.forEach((item, index, arr)=>{
+//     console.log(item, index, arr);
+// })
+
+const myCoding=[
+    {
+        languageName:"javascript",
+        languageFileName: "js"
+    },
+    {
+        languageName:"java",
+        languageFileName: "java"
+    },
+    {
+        languageName:"python",
+        languageFileName: "py"
+    },
+]
+
+myCoding.forEach((item)=>{
+    console.log(item.languageName);  
+})

05_iterations/four.js

@@ -0,0 +1,45 @@
+// Iterating through the objects
+const myObject ={
+    js: 'javascript',
+    cpp: 'C++',
+    rb: 'ruby',
+    swift: 'swift by apple'
+}
+//forin loop
+//Accessing the keys
+for (const key in myObject) {
+    //console.log(key);
+}
+//Accessing the values
+for (const key in myObject) {
+    //console.log(myObject[key]);
+}
+
+for(const key in myObject){
+    //console.log(`${key} shortcut is for ${myObject[key]}`);
+}
+
+//Can for in be used in arrays as well?
+
+const prog=['js','java','go','cpp','py']
+for (const key in prog) {
+    //console.log(key);
+}
+//This returns index positions of the elements in array
+for (const key in prog) {
+    //console.log(prog[key]);
+}
+
+//we can't iterate through maps
+const map= new Map()
+map.set('IN', "India")
+map.set('USA', "United States Of America")
+map.set('JP', "Japan")
+map.set('Fr', "France")
+map.set('IN', "India")
+
+for (const key in map) {
+    console.log(key);
+}
+//There is no output for this
+

05_iterations/one.js

@@ -0,0 +1,49 @@
+// for
+
+for (let i = 0; i <= 10; i++) {
+    const element = i;
+    if(element==5){
+        //console.log("5 is the best number");
+    }
+    //console.log(element); 
+}
+
+//Element is in loop, is not accessible outside due to scope
+
+for (let i = 1; i <=10; i++) {
+    //console.log(`Outer Loop value: ${i}`);
+    for (let j = 1; j <=10; j++) {
+        //console.log(`Inner Loop value ${j} and outer loop ${i}`); 
+        //console.log(i+' * '+j+' = '+i*j);
+         
+    }
+}
+
+let myArray= ["flash", "batman", "superman"]
+console.log(myArray.length);
+
+for (let index = 0; index < myArray.length; index++) {
+    const element = myArray[index];
+    console.log(element);
+}
+
+//In javascript, if we do action for out of bound indexes, we get undefined in its place
+// if condition of increasing the index is not there then, we get stuck in an infinite loop
+
+// break and continue
+
+// for (let index = 1; index <= 20; index++) {
+//     if(index==5){
+//         console.log("Detected 5");
+//         break
+//     }
+//     console.log(`Value of i is ${index}`);
+// }
+
+for (let index = 1; index <= 20; index++) {
+    if(index==5){
+        console.log("Detected 5");
+        continue
+    }
+    console.log(`Value of i is ${index}`);
+}

05_iterations/seven.js

@@ -0,0 +1,12 @@
+const myNumbers= [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+
+// const newNums= myNumbers.map( (num) => num+ 10)
+
+//Chaining
+//It means that we are able to apply multiple methods on top of one another
+const newNums= myNumbers.map((nums) => nums* 10)
+                .map((num)=>num*10)
+                .map((num)=>num+1)
+                .filter((num)=> num>=40)
+
+console.log(newNums);

05_iterations/six.js

@@ -0,0 +1,45 @@
+const coding = ["js", "ruby", "java", "python", "cpp"]
+
+// const values= coding.forEach((item)=>{
+//     // console.log(item);
+//     return item
+// })
+
+// console.log(values);
+//forEach doesn't return any values
+
+const myNums= [1,2,3,4,5,6,7,8,9,10]
+
+// const newNums= myNums.filter((num) => num>4)
+// console.log(newNums);
+
+// const newNums= myNums.filter((num) => {return num>4})
+// console.log(newNums);
+//If we use curly braces, then without return keyword nothing is returned
+
+const newNums = []
+
+myNums.forEach((num) => {
+    if(num>4){
+        newNums.push(num)
+    }
+})
+console.log(newNums);
+
+const books = [
+    { title: 'Book One', genre: 'Fiction', publish: 1981, edition: 2004 },
+    { title: 'Book Two', genre: 'Non-Fiction', publish: 1992, edition: 2008 },
+    { title: 'Book Three', genre: 'History', publish: 1999, edition: 2007 },
+    { title: 'Book Four', genre: 'Non-Fiction', publish: 1989, edition: 2010 },
+    { title: 'Book Five', genre: 'Science', publish: 2009, edition: 2014 },
+    { title: 'Book Six', genre: 'Fiction', publish: 1987, edition: 2010 },
+    { title: 'Book Seven', genre: 'History', publish: 1986, edition: 1996 },
+    { title: 'Book Eight', genre: 'Science', publish: 2011, edition: 2016 },
+    { title: 'Book Nine', genre: 'Non-Fiction', publish: 1981, edition: 1989 },
+  ];
+
+let userBooks= books.filter((bk) => bk.genre==="History")
+
+userBooks= books.filter((bk) => {return bk.publish>1995 && bk.genre==="History"})
+
+console.log(userBooks);

05_iterations/three.js

@@ -0,0 +1,56 @@
+// for of
+
+//They are array specific loops
+// ["", "", ""]
+// [{}, {}, {}]
+//We may have to handle multiple strings in array or mu;ltiple objects from an array
+
+const arr=[1, 2, 3, 4, 5]
+
+for(const num of arr){
+    //console.log(num);
+}
+
+const greetings= "Hello World!"
+for(const greet of greetings){
+    //console.log(`Each char is ${greet}`);   
+}
+
+//Maps
+
+const map= new Map()
+map.set('IN', "India")
+map.set('USA', "United States Of America")
+map.set('JP', "Japan")
+map.set('Fr', "France")
+map.set('IN', "India")
+//console.log(map);
+
+//Maps store unique values in same order as mentioned
+
+// These are forof loop
+
+for (const key of map) {
+    console.log(key);
+}
+//Output:
+/*
+[ 'IN', 'India' ]
+[ 'USA', 'United States Of America' ]
+[ 'JP', 'Japan' ]
+[ 'Fr', 'France' ]
+*/
+for (const [key,value] of map) {
+    console.log(key, ':-', value);
+}
+//Now the array is being destructured to give separate key, value pair
+
+const myObject={
+    game1: 'NFS',
+    game2: 'Spiderman'
+}
+// for (const [key, value] of myObject) {
+//     console.log(key, ':-', value);
+// }
+// The object myObject can't be iterated normal;y
+

05_iterations/two.js

@@ -0,0 +1,25 @@
+//while
+
+let index=0
+while(index<= 10){
+    //console.log(`Value of index is ${index}`);
+    index = index+2
+}
+
+let myArray= ['flash', 'batman', 'superman']
+
+let arr=0
+while(arr< myArray.length){
+    console.log(`Value is ${myArray[arr]}`);
+    arr=arr+1    
+}
+
+let score=11
+
+do{
+    console.log(`Score is ${score}`);
+    score++   
+}while(score<=10)
+
+//It executes for the first time without checking the condition for the first time
+