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Asked: 2026-05-26T12:02:57+00:00

I’m trying to write a simple javascript, or so I think, using while loops,

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I’m trying to write a simple javascript, or so I think, using “while” loops, “prompts”, and “alerts”.
I want the user to have a prompt to ask how many items he bought
then I want to take the number he entered and return the same number of prompts for the prices, then I want to use a while loop to total those prices up and add 7% sales tax to the whole thing, and then print the total off in an alert window

So here’s what I have so far:

<html> <head> <title> Meal Total </title>
    <script language="JavaScript">
        var result;
        meal=prompt("Number of Items: ");
     </script> <script language = "JavaScript">
var tip = 1.07; </script>
</head> <body bgcolor = "white"> <center> <script language = "JavaScript">
if (meal> 0) {
    var index = 0;
    while (index < meal) {
        prompt("price of the item");
        index = meal;
    }
};
else if (meal == 0) {
    alert("Number is 0");
} else if (meal <0) {
    alert("You entered is negative");
} </script></center> </body></html>

As you can see, I have most of the coding done. I have it detecting a negative or 0 for the number inputed. I need the followign things corrected: First, why does it ignore the number of prompts given for the imput value? When I open it and enter two, only 1 prompt window is shown. Second, how do I sum the prompt boxes?

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1 Answer

  1. Editorial Team

    You should clean up your code a bit:

    • Indent everything to make it more readable
    • Remove the <center> and bgcolor="white" parts since they do not add anything – your <center> element is empty, and a page is white by default and bgcolor is deprecated anyway
    • All your JavaScript code should be just in one block, no need for three of them. Also you should put all JavaScript into the head instead of mixing part of it into the body
    • Your code should not work because of your ; after the } of if, but since you said it worked partially this probably is not the problem. Be sure not to put ;s after if clauses, though.

    A working version: http://jsfiddle.net/pimvdb/2dqSr/.

    var result = 0; // result is 0 at first
var meal   = +prompt("Number of Items: "); // convert into a number with +
var tip    = 1.07;

if (meal > 0) {
    var index = 0;
    while (index < meal) {
        var price = +prompt("price of the item");
        result = result + price; // add price to result
        index++; // increment index, so that while loop will stop after 'meal' times.
                 // If you set it to 'meal' directly, then 'index' will be equal to
                 // 'meal' after the first iteration, and the while loop will only
                 // run once (after the first iteration 'index < meal' is false).
    }
    alert(result * tip); // alert total price * tip

} else if (meal == 0) {
    alert("Number is 0");

} else if (meal < 0) {
    alert("You entered is negative");
}
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