How to enter the strings from prompt into an array?

Question

Here's my code. I've tried a lot of things but it's not working. Please don't give me some complicated code, because I'm merely an intermediate programmer in javascript. So try to make things as simple as possible if you can. Thanks to everyone who helps.

function readNumberOfEntries() {
                var entryNumber, numberOfEntries, a;
                do {
                    numberOfEntries = Number(prompt("Enter Value Here"));
                    if (numberOfEntries < 2) {
                        alert("Error: Number is not greater than or equal to 2");
                    }
                } while (numberOfEntries < 2);
                for (entryNumber = 0; entryNumber < numberOfEntries; entryNumber++) {
                    a[entryNumber] = Number(prompt("Enter Value"));
                    a = new Array(numberOfEntries);
                    document.writeln(a);
                }
            }

Shouldn't a = new Array(numberOfEntries); and document.writeln(a); be outside the loop? Otherwise, you're creating a new array after each entered number, which deletes the previous one. And then you're printing an empty array numberOfEntries times. — anol
– anol, Commented Jul 24, 2015 at 19:21
Yea, that's probably why when I put 3 for number of entries in the prompt and then enter values: 1, 2, and 3, this is what I get: 1 1,2 1,2,3 — Khalil Hijazi
– Khalil Hijazi, Commented Jul 25, 2015 at 21:21

dhouty · Accepted Answer · 2015-07-27 17:23:05Z

2

The issue with your code is that you are overwriting your array in each iteration of the for loop. This should fix your problem:

function readNumberOfEntries() {
    var entryNumber, numberOfEntries, a;

    do {
        numberOfEntries = Number(prompt("Enter Value Here"));
        if (numberOfEntries < 2) {
            alert("Error: Number is not greater than or equal to 2");
        }
    } while (numberOfEntries < 2);

    a = new Array(numberOfEntries);  

    for (entryNumber = 0; entryNumber < numberOfEntries; entryNumber++) {
        a[entryNumber] = Number(prompt("Enter Value"));
    }

    document.writeln(a);
}

edited Jul 27, 2015 at 17:23

answered Jul 24, 2015 at 18:52

dhouty

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2 Comments

Khalil Hijazi Over a year ago

When I tried the code you gave me, this is what it gave me: 1,, 1,2, 1,2,3 So that's not working.

dhouty Over a year ago

That is because the document.writeln(a) expression was in the for loop, so the contents of the array got written on each iteration. I was under the impression that you were just using that statement for debugging purposes, so I left it in the loop body.

jrath · Accepted Answer · 2015-07-24 18:47:17Z

1

You should initialize your array before assignment/adding value into it.

      function readNumberOfEntries() {
            var entryNumber, numberOfEntries, a=[];
            do {
                numberOfEntries = Number(prompt("Enter Value Here"));
                if (numberOfEntries < 2) {
                    alert("Error: Number is not greater than or equal to 2");
                }
            } while (numberOfEntries < 2);
            for (entryNumber = 0; entryNumber < numberOfEntries; entryNumber++) {
               // a = new Array(numberOfEntries);
                a[entryNumber] = Number(prompt("Enter Value"));

                document.writeln(a);
            }
        }

answered Jul 24, 2015 at 18:47

jrath

9904 silver badges14 bronze badges

1 Comment

Khalil Hijazi Over a year ago

When I put 3 for number of entries in the prompt and then enter values: 1, 2, and 3, this is what I get: 1 1,2 1,2,3 It doesn't seem to be working, but I got it to work yesterday so thanks for the help.

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