London_Class_10 -Mehmet_Omer_Demir - JS-Core-1- Week-3

1-exercises/A-undefined/exercise.js

@@ -12,12 +12,13 @@
 // Example 1
 let a;
 console.log(a);
-
+//a dosen't have value
 
 // Example 2
 function sayHello() {
     let message = "Hello";
 }
+// This varibale is defined only inside of function and cannot be accessed outside the function
 
 let hello = sayHello();
 console.log(hello);
@@ -29,8 +30,9 @@ function sayHelloToUser(user) {
 }
 
 sayHelloToUser();
-
+// since the "sayHello()" function does not return any value, the variable "hello" is set to undefined
 
 // Example 4
 let arr = [1,2,3];
 console.log(arr[3]);
+// arr dosent have index 3

1-exercises/B-array-literals/exercise.js

@@ -5,7 +5,16 @@
 */
 
 let numbers = []; // add numbers from 1 to 10 into this array
-let mentors; // Create an array with the names of the mentors: Daniel, Irina and Rares
+
+for (let i=1; i<= 10 ;i++){
+  numbers.push(i)
+}
+
+
+// Create an array with the names of the mentors: Daniel, Irina and Rares
+
+let mentors = ['Daniel', 'Irina','Rares']
+
 
 /* 
   DO NOT EDIT BELOW THIS LINE

1-exercises/C-array-get-set/exercise.js

@@ -5,11 +5,11 @@
 */
 
 function first(arr) {
-  return; // complete this statement
+  return arr[0]; // complete this statement
 }
 
 function last(arr) {
-  return; // complete this statement
+  return arr[arr.length - 1]; // complete this statement
 }
 
 /* 

1-exercises/C-array-get-set/exercises2.js

@@ -7,6 +7,8 @@
 */
 
 let numbers = [1, 2, 3]; // Don't change this array literal declaration
+numbers.push(4)
+numbers[0]=1
 
 /* 
   DO NOT EDIT BELOW THIS LINE

1-exercises/D-for-loop/exercise.js

@@ -26,7 +26,11 @@ const AGES = [
     49
 ];
 
+
 // TODO - Write for loop code here
+for (let i=0 ;i < WRITERS.length; i++){
+    console.log(`${WRITERS[i]} is ${AGES[i]} years old`)
+}
 
 /*
 The output should look something like this:

1-exercises/E-while-loop-with-array/exercise.js

@@ -17,7 +17,14 @@ const BIRTHDAYS = [
 ];
 
 function findFirstJulyBDay(birthdays) {
+    let i=0
+    while (i<birthdays.length){
+        if(birthdays[i].includes("July")){
+            return birthdays[i];
+        }
+        i++;
     // TODO
-}
 
+}
+}
 console.log(findFirstJulyBDay(BIRTHDAYS)); // should output "July 11th"

2-mandatory/1-weather-report.js

@@ -12,7 +12,12 @@
 */
 
 function getTemperatureReport(cities) {
-    // TODO
+    let report = [];
+    for(let city of cities) {
+        let temperature = temperatureService(city);
+        report.push(`The temperature in ${city} is ${temperature} degrees`);
+    }
+    return report;
 }
 
 

2-mandatory/2-financial-times.js

@@ -5,16 +5,30 @@
     Implement the function below, which will return a new array containing only article titles which will fit.
 */
 function potentialHeadlines(allArticleTitles) {
+    let headlines=[];
+    for (let title of allArticleTitles )
+    if(title.length <= 65){
+        headlines.push(title);
+    }
+    return headlines;
     // TODO
-}
+}function titleWithFewestWords(allArticleTitles) {
+    let fewestWordsSoFar;
+    let titleWithFewestWords;
 
-/*
-    The editor of the FT likes short headlines with only a few words!
-    Implement the function below, which returns the title with the fewest words.
-    (you can assume words will always be seperated by a space)
-*/
-function titleWithFewestWords(allArticleTitles) {
-    // TODO
+    for(let title of allArticleTitles) {
+
+        // working out the number of words in the title by splitting on the space character
+        // this will generate an array. Read more: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split
+        let numWords = title.split(' ').length;
+
+        if(fewestWordsSoFar === undefined || numWords < fewestWordsSoFar) {
+            fewestWordsSoFar = numWords;
+            titleWithFewestWords = title;
+        }
+    }
+
+    return titleWithFewestWords;
 }
 
 /*
@@ -23,19 +37,42 @@ function titleWithFewestWords(allArticleTitles) {
     (Hint: remember that you can also loop through the characters of a string if you need to)
 */
 function headlinesWithNumbers(allArticleTitles) {
-    // TODO
+    let articlesWithNumbers = [];
+
+    for(let title of allArticleTitles) {
+        // Making use of the new function created below
+        if(doesTitleContainANumber(title)) {
+            articlesWithNumbers.push(title);
+        }
+    }
+
+    return articlesWithNumbers;
+}
+
+// Creating another function to help break this problem down into smaller parts
+function doesTitleContainANumber(title) {
+    for(let character of title) {
+        if(character >= '0' && character <= '9') {
+            return true;
+        }
+    }
+
+    return false;
 }
 
 /*
     The Financial Times wants to understand what the average number of characters in an article title is.
     Implement the function below to return this number - rounded to the nearest integer.
 */
 function averageNumberOfCharacters(allArticleTitles) {
-    // TODO
-}
-
+    let totalCharacters = 0;
 
+    for(let title of allArticleTitles) {
+        totalCharacters += title.length;
+    }
 
+    return Math.round(totalCharacters / allArticleTitles.length);
+}
 /* ======= List of Articles - DO NOT MODIFY ===== */
 const ARTICLE_TITLES = [
     "Streaming wars drive media groups to spend more than $100bn on new content",

2-mandatory/3-stocks.js

@@ -1,5 +1,5 @@
 /*
-    THESE EXERCISES ARE QUITE HARD. JUST DO YOUR BEST, AND COME WITH QUESTIONS IF YOU GET STUCK :)
+    THESE EXERCISES ARE QUITE HARD. DON'T WORRY IF YOU CAN'T COMPLETE THEM ALL - JUST DO YOUR BEST, AND COME WITH QUESTIONS :)
 
     Imagine we a working for a finance company. Below we have:
         - an array of stock tickers
@@ -33,8 +33,41 @@ const CLOSING_PRICES_LAST_5_DAYS_FOR_ALL_STOCKS = [
         Solve the smaller problems, and then build those solutions back up to solve the larger problem.
         Functions can help with this!
 */
+
+/*
+    SOLUTION EXPLANATION: This is a complex problem and there are many ways to solve it!
+        I've decided to break the large problem down into a few smaller problems.
+            1. The exercise is asking us to find the average price of EACH stock.
+                So first, maybe we can just work out how to get the average price for a SINGLE stock.
+                For this, I've created a separate function called getAveragePricesForStock.
+            2. We also need to work out how to round a number to 2 decimal places.
+                There's also a separate function for this called roundTo2Decimals.
+            3. We can put these smaller solutions back together to solve the larger problem.
+                The top-level getAveragePrices prices function can loop through the array,
+                and pass each sub-array to the getAveragePricesForStock function.
+*/
 function getAveragePrices(closingPricesForAllStocks) {
-    // TODO
+    let averages = [];
+
+    for(let pricesForStock of closingPricesForAllStocks) {
+        averages.push(getAveragePricesForStock(pricesForStock));
+    }
+
+    return averages;
+}
+
+function getAveragePricesForStock(pricesForStock) {
+    let total = 0;
+
+    for(let price of pricesForStock) {
+        total += price;
+    }
+
+    return roundTo2Decimals(total / pricesForStock.length);
+}
+
+function roundTo2Decimals(num) {
+    return Math.round(num * 100) / 100;
 }
 
 /*
@@ -47,8 +80,26 @@ function getAveragePrices(closingPricesForAllStocks) {
                 (Apple's price on the 5th day) - (Apple's price on the 1st day) = 172.99 - 179.19 = -6.2
     The price change value should be rounded to 2 decimal places, and should be a number (not a string)
 */
+
+/*
+    SOLUTION EXPLANATION: Again, we can break the large problem down into a few smaller problems.
+            1. I've created a new function which just calculates the change in price for a SINGLE stock - getPriceChangeForStock.
+            2. This new function can also use the roundTo2Decimals function we implemented earlier.
+                One of the many advatages of using functions is being able to re-use code!
+*/
 function getPriceChanges(closingPricesForAllStocks) {
-    // TODO
+    let changes = [];
+
+    for(let pricesForStock of closingPricesForAllStocks) {
+        changes.push(getPriceChangeForStock(pricesForStock))
+    }
+
+    return changes;
+}
+
+function getPriceChangeForStock(pricesForStock) {
+    let priceChange = pricesForStock[pricesForStock.length - 1] - pricesForStock[0]
+    return roundTo2Decimals(priceChange);
 }
 
 /*
@@ -61,10 +112,54 @@ function getPriceChanges(closingPricesForAllStocks) {
             For example, the first element of the array should be: "The highest price of AAPL in the last 5 days was 180.33"
             The test will check for this exact string.
     The stock ticker should be capitalised.
-    The price should be shown with exactly 2 decimal places.
+    The price should be shown with EXACTLY 2 decimal places.
+*/
+
+/*
+    SOLUTION EXPLANATION: We can also break this problem down into a smaller problems.
+            1. I've created a new function which just calculates the highest price for a SINGLE stock - getHighestPrice.
+            2. This new function can also use the roundTo2Decimals function we implemented earlier.
+    ALTERNATE SOLUTION: See highestPriceDescriptionsAlternate
+            I've included an alternate solution here which makes use of JavaScript's Math.max() function
+            https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/max
+            The Math.max() function takes zero or more numbers as input parameters.
+            We can convert our array into individual numbers that can then be passed into this function using the spread syntax: ...
+            Read more here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax
 */
 function highestPriceDescriptions(closingPricesForAllStocks, stocks) {
-    // TODO
+    let descriptions = [];
+
+    for(let i = 0; i < closingPricesForAllStocks.length; i++) {
+        let highestPrice = getHighestPrice(closingPricesForAllStocks[i]);
+        descriptions.push(`The highest price of ${stocks[i].toUpperCase()} in the last 5 days was ${highestPrice.toFixed(2)}`);
+    }
+
+    return descriptions;
+}
+
+function getHighestPrice(pricesForStock) {
+    // initialising to 0, as we're expecting this value to be overriden by the first price in the array
+    let highestPriceSoFar = 0;
+
+    for(let price of pricesForStock) {
+        // if this price is higher than the highest price we've seen so far, it becomes the new highest price
+        if(price > highestPriceSoFar) {
+            highestPriceSoFar = price;
+        }
+    }
+
+    return highestPriceSoFar;
+}
+
+function highestPriceDescriptionsAlternate(closingPricesForAllStocks, stocks) {
+    let descriptions = [];
+
+    for(let i = 0; i < closingPricesForAllStocks.length; i++) {
+        let highestPrice = Math.max(...closingPricesForAllStocks[i]);
+        descriptions.push(`The highest price of ${stocks[i].toUpperCase()} in the last 5 days was ${highestPrice.toFixed(2)}`);
+    }
+
+    return descriptions;
 }
 
 
@@ -91,4 +186,4 @@ test("should return a description of the highest price for each stock", () => {
             "The highest price of TSLA in the last 5 days was 1101.30"
         ]
     );
-});
+});