Cont'd Day1, completed functional programming exercises, will start classes next to begin the final process of finishing day 1.

solutions/day-01/functional_programming/level1.js

@@ -0,0 +1,115 @@
+const products = [
+    { product: 'banana', price: 3 },
+    { product: 'mango', price: 6 },
+    { product: 'potato', price: ' ' },
+    { product: 'avocado', price: 8 },
+    { product: 'coffee', price: 10 },
+    { product: 'tea', price: '' },
+]
+
+// Print the price of each product using forEach
+products.forEach(element => {
+    console.log(element.price);
+});
+
+
+// Print the product items as follows using forEach
+
+/*The price of banana is 3 euros.
+The price of mango is 6 euros.
+The price of potato is unknown.
+The price of avocado is 8 euros.
+The price of coffee is 10 euros.
+The price of tea is unknown.*/
+products.forEach(element => {
+    console.log(`The price of ${element.product} is ${(typeof element.price !== 'number') ? 'unknown.': element.price + ' euros.'}`);
+});
+
+
+// Calculate the sum of all the prices using forEach
+let sum = 0;
+products.forEach(element=>{
+    if(typeof element.price == 'number'){
+        sum += element.price
+    }
+});
+console.log(`Sum of all the prices is ${sum} euros.`);
+
+
+// Create an array of prices using map and store it in a variable prices
+let prices= products.map(element=>{
+    return element.price;
+})
+console.log(prices);
+
+
+// Filter products with prices
+products.filter(element=>{
+    if(typeof element.price == 'number'){
+        console.log(element);
+    }
+})
+
+
+// Use method chaining to get the sum of the prices(map, filter, reduce)
+let priceSum = products.map(element=>{
+    return element.price;
+}).filter(element=>{
+    if(typeof element == 'number'){
+        return element;
+    }
+}).reduce((a,b)=>{return a+b;})
+console.log(priceSum);
+
+
+// Calculate the sum of all the prices using reduce only
+let total = products.reduce((a, b)=>{
+    return parseInt(a + b.price);
+},0)
+console.log(total)
+
+
+// Find the first product which doesn't have a price value
+let found = products.find(element=>{
+    return typeof element.price !== 'number';
+})
+console.log(found);
+
+
+// Find the index of the first product which does not have price value
+let foundIndex = products.findIndex(element=>{
+    return typeof element.price !== 'number'
+})
+console.log(foundIndex);
+
+
+// Check if some products do not have a price value
+let hasValue = products.some(element=>{
+    return typeof element.price == 'number'
+})
+console.log(hasValue);
+
+
+// Check if all the products have price value
+let allHave = products.every(element=>{
+    return typeof element.price == 'number'
+})
+console.log(allHave);
+
+
+// Explain the difference between forEach, map, filter and reduce
+    // forEach lets you iterate through and array and can utilize index/array in the callback function
+    // map lets you perform a function on every element of an array and returns a new array 
+    // filter lets you filter items from an array and returns a new array with the filtered items
+    // reduce sums up all the items of the array 
+
+
+// Explain the difference between filter, find and findIndex
+    // filter lets you filter items from an array
+    // find lets you find and array element based on a given condition and returns the element
+    // findIndex is the same find except it returns an index value instead of the element itself
+
+
+// Explain the difference between some and every
+    // some - if one or some items satisfy criteria then return true else return false
+    // every - if all items satisfy criteria then return true else return false

solutions/day-01/functional_programming/script.js

@@ -40,7 +40,29 @@ console.log(sum);
 // - looks for first occurence of a certain array element.
 // returns first item that passes a test
 const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
-const found = numbers.find((element)=>{ return element > 4 && element < 8});
+const found = numbers.find((element)=>{return element > 4 && element < 8});
 console.log(found);
 
+// 6. findIndex
+// - works just like find() but returns index instead.
+const alphabet = ['A','B','C','D','E','F'];
+const index = alphabet.findIndex(element=>{return element == 'D'})
+console.log(`D is at index ${index}`);
 
+// 7. some
+// - some method is with arrays and returns a boolean.
+// - if one or some items satisfy criteria then return true else return false
+const digits = [0,1,2,3,4,5,6,7,8,9,10];
+const isEven = digits.some(element=>{return element % 2 === 0});
+const isOdd = digits.some(element =>{return element % 2 !== 0});
+console.log(`Array is even:`,isEven); //some values are even 
+console.log(`Array is odd:`,isOdd); // some values are odd
+
+// 8. every
+// -  every method is with arrays and returns a boolean
+// - is like some() methond BUT every item must statisfy the criteria
+/* using for testing const digits = [0,1,2,3,4,5,6,7,8,9,10];*/
+const isEven2 = digits.every(element=>{return element % 2 === 0});
+const isOdd2 = digits.every(element =>{return element % 2 !== 0});
+console.log(`Array is even:`,isEven2); // not every value is even 
+console.log(`Array is odd:`,isOdd2); // not every value is odd