JavaScript/Functions/Exercises
Topic: Functions
1. Define a function with one parameter. The function returns a string starting with "The given argument was: " and ends with ". Ok?". Insert the argument between those two strings.
"use strict"; // declare the function function decorate(str) { const ret = "The given argument is: " + str + ". Ok?"; return ret; } // call the function let tmp = decorate("Francis"); alert(tmp); tmp = decorate("Drake"); alert(tmp); 2. Extend the previous function to handle different data types, e.g., Numbers, Objects, ... . Show the data type into the returned string.
"use strict"; // declare the function function decorate(param) { let dataType = ""; let paramAsString = ""; switch (typeof param) { case "object": dataType = "object"; paramAsString = JSON.stringify(param); break; case "string": dataType = "string"; paramAsString = param; break; // next case ... default: dataType = "???"; paramAsString = param; } const ret = "The given argument is: " + paramAsString + " It's data type is: " + dataType + ". Ok?"; return ret; } // call the function let tmp = decorate("Francis"); alert(tmp); tmp = decorate(42); // a number alert(tmp); tmp = decorate({temperature: "25° C"}); // an object alert(tmp); 3. Define a function that takes two parameters. The function returns the average of both.
"use strict"; // declare the function function average(num1, num2) { return (num1 + num2) / 2; } // call the function alert(average(2, 4)); alert(average(2.4, 2.6)); 4. Define the function of the first exercise with an arrow function.
"use strict"; // declare the function and reverence it by a variable const decorate = (str) => "The given argument is: " + str + ". Ok?"; // call the function let tmp = decorate("Francis"); alert(tmp); // or, even more compact: tmp = (str => "The given argument is: " + str + ". Ok?")("Drake"); alert(tmp); 5. Define a function that takes an array of numbers as its parameter. The function returns the array's length, the smallest element, the largest element, and the average of all elements.
Because a function can return only a single element, all those computed values must be packed into an array (or an object). This array is the return value.
"use strict"; function checkArray(arr) { // local variables let min = arr[0]; let max = arr[0]; let sum = 0; // a 'forEach' construct with an anonymous function arr.forEach((elem) => { if (elem < min) { min = elem }; if (elem > max) { max = elem }; sum = sum + elem; }); // the length and average can be computed here // 'pack' everything in an array: [] return [arr.length, min, max, sum / arr.length]; } // the return value is an array let ret = checkArray([2, 4, 6, 8]); alert(ret); // or: let [length, min, max, avg] = checkArray([2, 4, 6, 8, 10]); alert ("Length: " + length + ", Min: " + min + ", Max: " + max + ", Average: " + avg); 6. Define a function for describing a car. It takes four parameters: producer, model, horsepower, and color. The first two are mandatory; the last two are optional. Define default values for the last two parameters, e.g., "unknown".
"use strict"; // supply default values if they are not given function showCar(producer, model, horsepower = "unknown", color = "unknown") { let ret = ""; if (!producer || !model) { return "Producer and model must be specified"; } ret = "My car is produced by " + producer; ret += ". The model is: " + model; ret += ". The horsepower is: " + horsepower; ret += ". The color is: " + color; return ret; } alert(showCar("Ford", "Mustang", 300, "blue")); alert(showCar("Ford", "Mustang GT", 350));