Reprompting a user for inputs using a while loop in javascript

Question

I am new to coding and trying some assignments. I am trying to prompt a user for the lengths of the sides of a triangle. The program calculates the area and returns a value. I am trying to use a while loop to reprompt the user if the given lengths do not create a triangle.

While (true)
{
    SideA = parseFloat(prompt("Enter the length of Side A"));
    SideB = parseFloat(prompt("Enter the length of Side B"));
    SideC = parseFloat(prompt("Enter the length of Side C"));

    //Calculate half the perimeter of the triangle
    S = parseFloat(((SideA+SideB+SideC)/2));

    //Calculate the area
    Area = parseFloat(Math.sqrt((S*(S-SideA)*(S-SideB)*(S-SideC))));

    if(isNaN(Area)) 
    {
        alert("The given values do not create a triangle. Please re- 
           enter the side lengths.");
    } 
    else 
    {
        break;
    }   

}

//Display results
document.write("The area of the triangle is " + Area.toFixed(2) + "." 
+ PA);

while(!isValidTriangle(one, two, three)) { prompt("Enter lengths") }. — Jack Bashford
– Jack Bashford, Commented Jun 15, 2019 at 23:10

Dileep · Accepted Answer · 2019-06-16 06:23:59Z

1

You can use a do while loop to achieve this:

function checkTriangleInequality(a, b, c) {
   return a < b + c && b < c + a && c < b + a;
}

function promptSides() {
  let a, b, c;
   while (true) {
    a = parseFloat(prompt("Enter a"));
    b = parseFloat(prompt("Enter b"));
    c = parseFloat(prompt("Enter c"));

    if (!checkTriangleInequality(a, b, c)) {
      alert("Input is invalid, please try again.")
    } else {
      let s = (a+b+c)/2
      let area = parseFloat(Math.sqrt((s*(s-a)*(s-b)*(s-c))));
      console.log(area);
      break;
    }
   }
}

edited Jun 16, 2019 at 6:23

answered Jun 16, 2019 at 0:49

Dileep

1741 silver badge8 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Kevown Bechard Over a year ago

Thank you! I have this portion running smoothly. Where would be the ideal place to enter an alert that tells the user the inputs are invalid and to re-enter them? I do not want it to appear the first time it runs so I'm not sure how to make it work using this structure.

Collectives™ on Stack Overflow

Reprompting a user for inputs using a while loop in javascript

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related