From ec1cba346a41deabd07e11ddc52f7f9157ae06e4 Mon Sep 17 00:00:00 2001
From: Savitha <gsavitha@protonmail.com>
Date: Fri, 13 Jan 2023 17:29:41 +0530
Subject: [PATCH] Complete solutions for callbacks

---
 callbacks.js | 302 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 302 insertions(+)

diff --git a/callbacks.js b/callbacks.js
index 0466603..9901929 100644
--- a/callbacks.js
+++ b/callbacks.js
@@ -130,3 +130,305 @@ function objectFilter(obj, callback) {
 //   Paris: 'PARIS',
 // };
 // console.log(objectFilter(cities, city => city.toUpperCase())) // Should log { London: 'LONDON', Paris: 'PARIS'}
+
+
+//Extension 8
+function majority(array, callback) {
+  let countT = 0;
+  let countF = 0;
+  for (let i = 0; i < array.length; i++) {
+    callback(array[i]) ? ++countT : ++countF;
+  }
+
+  return countT > countF;
+}
+
+// /*** Uncomment these to check your work! ***/
+// const isOdd2 = function(num) { return num % 2 === 1; };
+// console.log(majority([1, 2, 3, 4, 5], isOdd2)); // should log: true
+// console.log(majority([2, 3, 4, 5], isOdd2)); // should log: false
+
+//Extension 9
+function prioritize(array, callback) {
+  const res = [];
+  for (let i = 0; i < array.length; i++) {
+    if (callback(array[i])) {
+      res.push(array[i]);
+    }
+  }
+  for (let i = 0; i < array.length; i++) {
+    if (!callback(array[i])) {
+      res.push(array[i]);
+    }
+  }
+  return res;
+}
+
+// /*** Uncomment these to check your work! ***/
+// const startsWithS = function(str) { return str[0] === 's' || str[0] === 'S'; };
+// console.log(prioritize(['curb', 'rickandmorty', 'seinfeld', 'sunny', 'friends'], startsWithS));
+// should log: ['seinfeld', 'sunny', 'curb', 'rickandmorty', 'friends']
+
+//Extension 10
+function countBy(array, callback) {
+  const res = {};
+  let countO = 0,
+    countE = 0;
+  for (let num of array) {
+    let key = callback(num);
+    key === "odd" ? (res[key] = ++countO) : (res[key] = ++countE);
+  }
+  return res;
+}
+
+// /*** Uncomment these to check your work! ***/
+// console.log(countBy([1, 2, 3, 4, 5], function(num) {
+// if (num % 2 === 0) return 'even';
+// else return 'odd';
+// }));
+// should log: { odd: 3, even: 2 }
+
+//Extension 11
+function groupBy(array, callback) {
+  const res = {};
+  for (let i of array) {
+    let dec = callback(i);
+    if (dec in res) {
+      res[dec].push(i);
+    } else {
+      res[dec] = [i];
+    }
+  }
+  return res;
+}
+
+//using reduce
+function groupBy(array, callback) {
+  return array.reduce((res, i) => {
+    const dec = callback(i);
+    if (dec in res) {
+      res[dec].push(i);
+    } else {
+      res[dec] = [i];
+    }
+    return res;
+  }, {});
+}
+
+// /*** Uncomment these to check your work! ***/
+// const decimals = [1.3, 2.1, 2.4];
+// const floored = function(num) { return Math.floor(num); };
+// console.log(groupBy(decimals, floored));
+// should log: { 1: [1.3], 2: [2.1, 2.4] }
+
+//Extension 12
+function goodKeys(obj, callback) {
+  const res = [];
+  for (let key in obj) {
+    if (callback(obj[key])) {
+      res.push(key);
+    }
+  }
+  return res;
+}
+
+// /*** Uncomment these to check your work! ***/
+// const sunny = { mac: 'priest', dennis: 'calculating', charlie: 'birdlaw', dee: 'bird', frank: 'warthog' };
+// const startsWithBird = function(str) { return str.slice(0, 4).toLowerCase() === 'bird'; };
+// console.log(goodKeys(sunny, startsWithBird)); // should log: ['charlie', 'dee']
+
+//Extension 13
+function commutative(func1, func2, value) {
+  let op = func2(func1(value));
+  let op2 = func1(func2(value));
+
+  return op === op2;
+}
+
+// /*** Uncomment these to check your work! ***/
+// const multBy3 = (n) => n * 3;
+// const divBy4 = (n) => n / 4;
+// const subtract5 = (n) => n - 5;
+// console.log(commutative(multBy3, divBy4, 11)); // should log: true
+// console.log(commutative(multBy3, subtract5, 10)); // should log: false
+// console.log(commutative(divBy4, subtract5, 48)); // should log: false
+
+//Extension 14
+function objFilter(obj, callback) {
+  const res = {};
+
+  for (let key in obj) {
+    if (obj[key] === callback(key)) {
+      res[key] = obj[key];
+    }
+  }
+  return res;
+}
+
+// /*** Uncomment these to check your work! ***/
+// const startingObj = {};
+// startingObj[6] = 3;
+// startingObj[2] = 1;
+// startingObj[12] = 4;
+// const half = (n) => n / 2;
+// console.log(objFilter(startingObj, half)); // should log: { 2: 1, 6: 3 }
+
+//Extension 15
+function rating(arrOfFuncs, value) {
+  let count = 0;
+  for (let func of arrOfFuncs) {
+    if (func(value)) {
+      count++;
+    }
+  }
+
+  return (count / arrOfFuncs.length) * 100;
+}
+
+// Using filter
+
+function rating(arrOfFuncs, value) {
+  if (arrOfFuncs.length === 0) return 0;
+  const count = arrOfFuncs.filter((func) => func(value)).length;
+  return (count / arrOfFuncs.length) * 100;
+}
+// /*** Uncomment these to check your work! ***/
+// const isEven = (n) => n % 2 === 0;
+// const greaterThanFour = (n) => n > 4;
+// const isSquare = (n) => Math.sqrt(n) % 1 === 0;
+// const hasSix = (n) => n.toString().includes("6");
+// const checks = [isEven, greaterThanFour, isSquare, hasSix];
+// console.log(rating(checks, 64)); // should log: 100
+// console.log(rating(checks, 66)); // should log: 75
+
+//Extension 16
+function pipe(arrOfFuncs, value) {
+  let result = value;
+  for (let func of arrOfFuncs) {
+    result = func(result);
+  }
+  return result;
+}
+
+//Using reduce
+
+function pipe(arrOfFuncs, value) {
+  return arrOfFuncs.reduce((acc, func) => func(acc), value);
+}
+
+// /*** Uncomment these to check your work! ***/
+// const capitalize = (str) => str.toUpperCase();
+// const addLowerCase = (str) => str + str.toLowerCase();
+// const repeat = (str) => str + str;
+// const capAddlowRepeat = [capitalize, addLowerCase, repeat];
+// console.log(pipe(capAddlowRepeat, "cat")); // should log: 'CATcatCATcat'
+
+//Extension 17
+function highestFunc(objOfFuncs, subject) {
+  let highestKey = null;
+  let highestResult = -Infinity;
+
+  for (let key of Object.keys(objOfFuncs)) {
+    let result = objOfFuncs[key](subject);
+
+    if (result > highestResult) {
+      highestKey = key;
+      highestResult = result;
+    }
+  }
+  return highestKey;
+}
+
+// Using Object.entries
+
+function highestFunc(objOfFuncs, subject) {
+  let highestKey = null;
+  let highestResult = -Infinity;
+
+  //Iterate over keys and values in a single loop instead of writing `Object.keys` and getting its value from key
+  for (const [key, func] of Object.entries(objOfFuncs)) {
+    let result = func(subject);
+
+    if (result > highestResult) {
+      highestKey = key;
+      highestResult = result;
+    }
+  }
+  return highestKey;
+} // /*** Uncomment these to check your work! ***/
+// const groupOfFuncs = {};
+// groupOfFuncs.double = (n) => n * 2;
+// groupOfFuncs.addTen = (n) => n + 10;
+// groupOfFuncs.inverse = (n) => n * -1;
+// console.log(highestFunc(groupOfFuncs, 5)); // should log: 'addTen'
+// console.log(highestFunc(groupOfFuncs, 11)); // should log: 'double'
+// console.log(highestFunc(groupOfFuncs, -20)); // should log: 'inverse'
+
+//Extension 18
+function combineOperations(startVal, arrOfFuncs) {
+  // let result = startVal;
+  // for(let func of arrOfFuncs){
+  //   result = func(result);
+  // }
+  // return result;
+
+  //using reduce
+
+  // return arrOfFuncs.reduce((acc,func)=>func(acc),startVal)
+
+  //utilising the previously written func
+  return pipe(arrOfFuncs, startVal);
+}
+
+function add100(num) {
+  return num + 100;
+}
+
+function divByFive(num) {
+  return num / 5;
+}
+
+function multiplyByThree(num) {
+  return num * 3;
+}
+
+// /*** Uncomment these to check your work! ***/
+// console.log(combineOperations(0, [add100, divByFive, multiplyByThree])); // Should output 60 -->
+// console.log(combineOperations(0, [divByFive, multiplyByThree, add100])); // Should output 100
+
+//Extension 19
+function myFunc(array, callback) {
+  for (let i = 0; i < array.length; i++) {
+    if (callback(array[i])) return 1;
+  }
+  return -1;
+}
+
+const numbers = [2, 3, 6, 64, 10, 8, 12];
+const evens = [2, 4, 6, 8, 10, 12, 64];
+
+function isOdd(num) {
+  return num % 2 !== 0;
+}
+
+// /*** Uncomment these to check your work! ***/
+// console.log(myFunc(numbers, isOdd)); // Output should be 1
+// console.log(myFunc(evens, isOdd)); // Output should be -1
+
+//Extension 20
+function myForEach(array, callback) {
+  for (let i = 0; i < array.length; i++) {
+    callback(array[i]);
+  }
+}
+
+let sum = 0;
+
+function addToSum(num) {
+  sum += num;
+}
+
+// /*** Uncomment these to check your work! ***/
+// const nums2 = [1, 2, 3];
+// myForEach(nums2, addToSum);
+// console.log(sum); // Should output 6