How to reference a previous prompt() in JavaScript?

Question

I want to ask a user (through a prompt) if they would rather convert km to miles, or miles to km, within an else if statement. If neither condition is met, I want to go back to the conversion prompt:

var conversion = prompt("Do you want to convert miles to km, or km to miles?");
if (conversion=="miles to km") {
  [perform miles conversion here]
} else if (conversion=="km to miles") {
  [perform km conversion here]
} else {
  [go back to conversion prompt]
}

How would you code this line in JavaScript? Thanks.

while(true) { do stuff }

Marc B
– Marc B

2016-02-01 18:49:44 +00:00
Commented Feb 1, 2016 at 18:49 — Marc B
– Marc B, Commented Feb 1, 2016 at 18:49

Jorel Amthor · Accepted Answer · 2016-02-01 19:01:20Z

1

var userHasMadeAChoice = false;

while(!userHasChosen)
{
    var conversion=prompt("Do you want to convert miles to km, or km to miles?");
    if (conversion=="miles to km") {
        [perform miles conversion here]
        userHasMadeAChoice = true;
    } else if (conversion=="km to miles") {
        [perform km conversion here]
        userHasMadeAChoice = true;
    }
}

Please do consider reading various articles on Structured Programming

answered Feb 1, 2016 at 19:01

Jorel Amthor

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Comments

TGrif · Accepted Answer · 2016-02-01 19:45:31Z

1

I could do it like that:

    var conversion;

    while (conversion === null || (conversion !== "miles to km" && conversion !== "km to miles")) {
        conversion = prompt('Do you want to convert miles to km, or km to miles?');
    }

    console.log(conversion);

edited Feb 1, 2016 at 19:45

answered Feb 1, 2016 at 19:40

TGrif

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1 Comment

brso05 Over a year ago

No problem. This is a nice solution.

brso05 · Accepted Answer · 2016-10-12 19:29:10Z

0

Use a loop:

while(true)
{
    var conversion=prompt("Do you want to convert miles to km, or km to miles?");
    if (conversion=="miles to km") {
        [perform miles conversion here]
        break;
    } else if (conversion=="km to miles") {
        [perform km conversion here]
        break;
    }
}

You can use a while loop and just set the condition to true. Then break out of the loop using break when one of the conditions is met.

answered Oct 12, 2016 at 19:29

brso05

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