Add: Interview concept (HOF)

JS/HOF [11-05-2024]/program1.js

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+// HOF -> Higher Order Function
+
+function x() {
+   let x = 10;
+   console.log("Value of x", x);
+}
+
+function hof(f) {
+   console.log("Value of f", f);
+   f()
+}
+
+hof(x) // hof 
+// x is a callback function
+
+// HOF
+// A function that takes another function as its argument.
+// for example: hof()
+
+// callback function
+// A function which is passed as an argument
+// for example: x()

JS/HOF [11-05-2024]/program10.js

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+// We need to filter out those names who can vote
+
+let people = [
+   {
+      name: "Huzaifa",
+      age: 52,
+   },
+   {
+      name: "Parth",
+      age: 25,
+   },
+   {
+      name: "Sumit",
+      age: 15,
+   },
+   {
+      name: "Rinka",
+      age: 13,
+   },
+   {
+      name: "Tushar",
+      age: 18,
+   },
+];
+
+// let votingNames = people.filter(({age}, index, array) => {
+//    return age >= 18;
+// });
+
+let votingNames = people.filter(({ age }) => age >= 18);
+
+console.log(votingNames);
+
+
+// Homework:
+// sort

JS/HOF [11-05-2024]/program2.js

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+// HOF
+// Callback
+
+
+// Program 1:
+
+function jack(x) {
+
+}
+
+function sparrow(x) {
+
+}
+
+sparrow(jack)
+
+// callback -> jack
+// hof -> sparrow
+
+
+// Program 2
+
+function add() {
+
+}
+
+function subtract() {
+
+}
+
+function mutiple() {
+
+}
+
+function divide() {
+
+}
+
+divide(mutiple) // hof -> divide callback -> multiple
+add(subtract) // callback -> subtract hof -> add
+

JS/HOF [11-05-2024]/program3.js

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+/*
+array methods + hof:
+
+forEach
+map
+filter
+reduce
+*/
+
+let arr = [1, 2, 3];
+
+arr.forEach()

JS/HOF [11-05-2024]/program4.js

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+// forEach
+
+let arr = [
+   "Mango",
+   "Apple",
+   "Orange",
+   "Watermelon",
+   "Chiku",
+   "Banana",
+   "Lichi",
+];
+
+// Tell me the index number of 'Watermelon' in my array
+
+arr.forEach(function (element, index, array) {
+   if (element === "Lichi") {
+      console.log(index);
+   }
+});

JS/HOF [11-05-2024]/program5.js

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+let arr = [1, 2, 3, 4, 5];
+
+let sum = 0;
+let product = 1;
+arr.forEach(function (element, index, array) {
+   sum = sum + element;
+   product = product * element;
+});
+
+console.log("Sum of array", sum);
+console.log("Product of array", product);

JS/HOF [11-05-2024]/program6.js

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+let sumOfArr = 0;
+
+function sum(element, index, array) {
+    sumOfArr += element;
+}
+
+let arr = [1, 2, 3, 4, 5];
+
+let x = arr.forEach(sum);
+
+// console.log(sumOfArr);
+console.log(x);

JS/HOF [11-05-2024]/program7.js

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+// Tell me the difference between forEach and map?
+
+// 1. map returns an array whereas forEach does not
+// 2. If you just want to iterate over your array, then go ahead with forEach
+// 3. If you want to create a new array, then go ahead with map
+// some examples
+
+// HOF
+// map
+
+let arr = [1, 2, 3, 4, 5];
+// element -> square
+// updated -> [1, 4, 9]
+
+// [ 1, 4, 9, 16, 25]
+// element = 3
+// index = 2
+let x = arr.map(function (element, index, array) {
+    return element ** 2; // 3**2 -> 9
+})
+
+console.log("Value of x", x);
+
+// for (let i = 0; i < arr.length; i++) {
+//    arr[i] = arr[i] ** 2;
+// }
+
+// console.log(arr);

JS/HOF [11-05-2024]/program8.js

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+// filter
+// In filter, return inside the function expects a Boolean value
+
+function isPrime(num) {
+   let factor = 0;
+   for (let i = 1; i <= num; i++) {
+      if (num % i === 0) {
+         factor++;
+      }
+   }
+   return factor === 2;
+}
+
+let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+
+// element = 4
+// index = 3
+// x = [2, 4]
+let x = arr.filter(function (element) {
+   return element > 5;
+});
+
+console.log(x);
+
+// let newArr = [];
+// for (let i = 0; i < arr.length; i++) {
+//    if (arr[i] % 2 === 1) {
+//       newArr.push(arr[i]);
+//    }
+// }
+
+// console.log(newArr);

JS/HOF [11-05-2024]/program9.js

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+// reduce
+// accumulator -> default -> 0
+
+let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+
+// index = 9
+// element = 10
+// accumulator = 55
+let x = arr.reduce(function (accumulator, element, index, array) {
+   return `${accumulator} ${element}`;
+}, "");
+
+console.log(x);