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JavaScript

Gareth Moore
Gareth Moore
7,724 Points
Posted by Gareth Moore
Gareth Moore
7,724 Points

Solution using Arrays to prompt for user input :) 

// FUNCTIONS for area and volume calculations
function areaRect(num1, num2) {
  const output = num1 * num2;
  return(output);
}
function volRect(num1, num2, num3) {
  const output = num1 * num2 * num3;
  return(output);
}
function areaCir(num1) {
  const output = Math.PI * Math.pow(num1, 2);
  return(output);
}
function volSphere(num1){
  const output = (4/3) * Math.PI * Math.pow(num1, 3);
  return(output);
}


// PROMPT user for dimensions of shapes. Store in const array (using function below: inputNum)
const input = [inputNum("width"), inputNum("length"), inputNum("height"), inputNum("radius")];
// FUNCTION for user input and user input evaluation as number
function inputNum(dimension){
  let input = prompt(`Please enter the ${dimension} value:`);
  while (isNaN(input)) {
    input = prompt(`That was not a valid number. Please type a ${dimension} value:`);
  }
  return(input);
}


// Output the area and volume calculation in html
document.querySelector('body').innerHTML = `
<h1>Here are the results!!</h1>
<p>The area of your rectangle is ${areaRect(input[0], input[1])}</p>
<p>The volume of your rectangle is ${volRect(input[0], input[1], input[2])}</p>
<p>The area of your circle is ${areaCir(input[3])}</p>
<p>The volume of your sphere is ${volSphere(input[3])}</p>`;

//Hope this helped you in some way :)

2 Answers

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

Very clever! :+1:

But be aware that the return from prompt is always a string. The isNaN test works because the argument is coerced into a number, but some operations could produce unexpected results. For example, if a + operator were used, it would be interpreted as concatenation instead of addition. To prevent this, you can explicitly convert the input into numbers using parseInt:

  let input = parseInt(prompt(`Please enter the ${dimension} value:`));
  while (isNaN(input)) {
    input = parseInt(prompt(`That was not a valid number. Please type a ${dimension} value:`));
  }

Also, it occurred to me that map might provide a clever way to acquire the input:

const input = ["width", "length", "height", "radius"].map(a => inputNum(a));
Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

The implicit coercion I mentioned before can be confusing and have unexpected results. The isNaN function first tries to convert its argument into a number, and then checks if the result is NaN. So a string containing digits will still get a false result even though it is a string and not an actual number. Coercion also happens for some math operations, but not if the operator has a different meaning for strings (like + does).

Gareth Moore
Gareth Moore
7,724 Points
Gareth Moore
Gareth Moore
7,724 Points

Thanks for your advice Steven :)

Would you mind explaining a little bit more. I am not sure I fully understand you.

My thinking is that whatever string the user inputs via the prompt function, it will be passed through the isNaN function. The isNaN function (as far as I am aware) evaluates a value to see if it is a number variable or not. So if it is false then the user input is a number. If it is true then the user input isn't a number (a string or whatever else it could be). So can the isNaN function return a value of say +4 as a number variable? Or am I missing something else entirely haha.

Again, thanks for your help!

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

See the comment I added to my answer.