London Class 10- Yuliya Hospodar- JavaScript-Core-1-Coursework-Week3

1-exercises/A-undefined/exercise.js

@@ -10,17 +10,20 @@
 */
 
 // Example 1
-let a;
+let = a;
 console.log(a);
 
+// In this example an operator "=" was absent
 
 // Example 2
 function sayHello() {
     let message = "Hello";
+    return message;
 }
 
 let hello = sayHello();
 console.log(hello);
+// The mistake was inside function body, where return was absent that is why we've seen undefined
 
 
 // Example 3
@@ -30,7 +33,11 @@ function sayHelloToUser(user) {
 
 sayHelloToUser();
 
+// Inside function parameter braces should be parameter when the function is called 
 
 // Example 4
 let arr = [1,2,3];
 console.log(arr[3]);
+
+// When we call array elements via arr[] method we need to consider that index starts from 0 in arr, that's 
+// we see undefined because we call 4th element

2-mandatory/1-weather-report.js

@@ -1,21 +1,26 @@
-/*
-    Imagine we're making a weather app!
-
-    We have a list of cities that the user wants to track.
-    We also already have a temperatureService function which will take a city as a parameter and return a temparature.
+    /*
+        Imagine we're making a weather app!
+        
+        We have a list of cities that the user wants to track.
+        We also already have a temperatureService function which will take a city as a parameter and return a temparature.
 
-    Implement the function below:
-        - take the array of cities as a parameter
-        - return an array of strings, which is a statement about the temperature of each city.
-            For example, "The temperature in London is 10 degrees"
-        - Hint: you can call the temperatureService function from your function
-*/
+        Implement the function below:
+            - take the array of cities as a parameter
+            - return an array of strings, which is a statement about the temperature of each city.
+                For example, "The temperature in London is 10 degrees"
+            - Hint: you can call the temperatureService function from your function
+    */
 
 function getTemperatureReport(cities) {
-    // TODO
+    const report = [];
+        for (const city of cities) {
+            const temperature = temperatureService(city);
+            const message = `The temperature in ${city} is ${temperature} degrees`;
+            report.push(message);
+        }
+    return report;
 }
 
-
 /* ======= TESTS - DO NOT MODIFY ===== */
 
 function temperatureService(city) {

2-mandatory/2-financial-times.js

@@ -5,7 +5,15 @@
     Implement the function below, which will return a new array containing only article titles which will fit.
 */
 function potentialHeadlines(allArticleTitles) {
-    // TODO
+   let headlines = [];
+
+   for(let title of allArticleTitles) {
+       if(title.length <= 65) {
+        headlines.push(title);
+       }
+    }
+
+    return headlines;
 }
 
 /*
@@ -14,7 +22,21 @@ function potentialHeadlines(allArticleTitles) {
     (you can assume words will always be seperated by a space)
 */
 function titleWithFewestWords(allArticleTitles) {
-    // TODO
+    let fewestWordsSoFar;
+    let titleWithFewestWords;
+
+    for(let title of allArticleTitles) {
+
+        // working out the number of words in the title by splitting on the space character
+        //this will create an array
+        let shortWords = title.split('').length;
+
+        if(fewestWordsSoFar === undefined || shortWords < fewestWordsSoFar) {
+            fewestWordsSoFar = shortWords;
+            titleWithFewestWords = title;
+        }
+    }
+   return titleWithFewestWords;
 }
 
 /*
@@ -23,15 +45,41 @@ 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 that helps break this problem down into smaller pieces
+function doesTitleContainANumber(titele) {
+    for(let character of titele) {
+        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 titele of allArticleTitles) {
+        totalCharacters +=titele.length;
+    }
+
+    return Math.round(totalCharacters / allArticleTitles.length);
 }
 
 

2-mandatory/3-stocks.js

@@ -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 quite a complex problem and there are several ways to solve it.
+          I decided to divide the big problem into several smaller ones.
+              1. In the exercise we are asked to find the average price of EACH stock.
+                  So maybe we can just work out how to get the average price for a single stock.
+                  To do this, I created a separate function called getAveragePricesForStock.
+              2. We also need to work out how to round a number to 2 decimal places.
+                  There is also a separate function for this called roundTo2Decimals.
+              3. We can put these smaller solutions together to solve a bigger problem.
+                  The top-level price function getAveragePrices can loop through an array,
+                  and pass each subarray 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 +80,27 @@ 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, as in the previous solution, we can divide a large problem into several smaller ones.
+              1. I created a new function that simply calculates the price change of ONE stock - getPriceChangeForStock.
+              2. This new function can also use the roundTo2Decimals function we used before.
+                  One of the biggest benefits of using this feature is the ability to reuse 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);
 }
 
 /*
@@ -63,10 +115,55 @@ function getPriceChanges(closingPricesForAllStocks) {
     The stock ticker should be capitalised.
     The price should be shown with exactly 2 decimal places.
 */
+
+/*
+    EXPLANATION : We can also break this problem down into smaller problems.
+                1. I created a new function that simply calculates the highest price for a single stock - getHighestPrice.
+                2. This new function can also use the roundTo2Decimals function
+               Here I have included an alternative solution that uses JavaScript's Math.max() function
+                The Math.max() function accepts zero or more numbers as input parameters.
+                We can convert our array into individual numbers, which can then be passed to this function using the propagation 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 are 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 highestprice we are seen so far, it becomes the new highest price
+        if(price > highestPriceSoFar) {
+            highestPriceSoFar = price;
+        }
+    }
+
+    return highestPriceSoFar;
 }
 
+function highestPriceDescriptionsAllternate(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;
+
+}
+
+
 
 /* ======= TESTS - DO NOT MODIFY ===== */
 test("should return the average price for each stock", () => {