CALCULATOR For this task, you will create a simple calculator that performs addition, subtraction, multiplication, and division. Open the file calculator.html in your browser to see what your calculator will look like. Upon clicking the "Calculate!" button, your program should prompt the user for a number, an operator (+,-,", or /), and another number. It should then print the input and answer on the calculator screen as shown in the examples. We have already set up the button on the page to call the function promptUser() when a user clicks it. The expectations for each of the three functions you must define are outlined below. You may find it easiest to work on one function at a time, checking your progress as you go by printing to the console. PROMPTUSER() FUNCTION The promptUser() function should first give the user three separate prompts for the first number, operator, and second number, respectively. The three separate prompt() calls to get the user input should be (in this order): "Enter first number: " "Enter operator (+, -, , or /): " "Enter second number: " It should then call the calc(x, operator, y) function to get the answer. Finally, it should call the printAnswer(x, operator, y, answer) function to print the answer to the page. CALC(X, OPERATOR, Y) FUNCTION The calc(x, operator, y) function takes the two numbers and operator as input and returns the answer. The parameters x and y should be the first and second numbers, respectively. The parameter operator is whatever operator the user entered. E.g., if the user enters "3", "+", and "5" (without the quotes), then this function should return "8". Input assumptions: You can assume the user gives you valid numbers for the two numbers. However, they may enter anything for the operator. If the operator they enter is not +, -, *, or /, then this function should return NaN (the javascript object NaN, not the string "NaN"). PRINTANSWER(X, OPERATOR, Y, ANSWER) FUNCTION The printAnswer(x, operator, y, answer) function take the two numbers, operator, a answer as input. It prints the full equation to the page by adding it in a paragraph () to the element with id="calculatorDisplay". Note that to add a string to the end without replacing what's currently there, you use += instead of =. For example, executing the following line of code would add "5*2= 10": document.getElementById("calculatorDisplay").innerHTML += "5 2 = 10"; If the answer is NaN the paragraph element added should belong to the class badinput. This will cause the text to display in red (as defined by the CSS rules for that class in calculator.css). You can check whether the answer is NaN using the existing function isNaN(). You can learn more about isNaN() here. Note that this function should not return anything. It simply adds another line to the display. The HTML file, calculator.html, starts with a few lines displayed in the calculator to illustrate what the output should look like. Your printAnswer(x, operator, y, answer) function should NOT replace the existing text. It should just add a new line each time. After adding a few lines, the CSS will automatically add a scroll bar to scroll down to the most recent line. The following picture shows what should display if the first query is 3.7