Why doesn't my variable save to my array in JavaScript?

Question

Hello I have a piece of code that checks a value against an array and if that value is not found in the array, then it adds that value to another array (called the soldListingArray). It then saves the soldListingArray to the localStorage (using localStorage.setItem("array", soldListingArray). For some reason, in my console I can see that the variable is the correct one, after adding it to the array, but outside of the code when I call for the entire array, it says it's empty.

array1 is the array I'm checking all the values inside against the array2 array.

Here is my code:

    function checkToSeeIfListingIsSold() {

    var soldListingArray = localStorage.getItem("array");

    var x = 0;
    var y = array1.length;

    do {

        var index = array1[x];

        if (array2.indexOf(index) == -1) {

            // Here I add the variable to my soldListingArray

            soldListingArray[soldListingArray.length] = index;

            // Here my console says what has been added to the soldListingArray (the value is correct).

            console.value += index + " has been added to soldListingArray;\n";
            }

         x++;

        } while (x < y)

   localStorage.setItem("array", soldListingArray);

   // Here I ask my console to display my soldListingArray but I get an empty array back.

   console.value += "Sold Array: " + soldListingArray;

   }

Why wasn't the index variable added and saved to my soldListingArray?

Any help is appreciated! Thanks in advance.

hmm... seems like you never converted `soldListingArray` to an array. When you pull it from localstorage, it is a string. — Kevin B, Jan 28 '15 at 20:58
@KevinB - And then, technically, it behaves like an array of chars — LcSalazar, Jan 28 '15 at 21:00
Why don't you use `soldListingArray.push(index)` and `localStorage.push(soldListingArray);` ? — Fenistil, Jan 28 '15 at 21:01
@KevinB No I actually already have saved an "a" into my `soldListingArray` (I saved it as an array) and when I call it, it displays the "a" but nothing else. Am I missing something though? — The Man, Jan 28 '15 at 21:03
Oh sorry, because of sg. I thought that localStorage is also an array.. :( — Fenistil, Jan 28 '15 at 21:03
@TheMan Right, but when you pull it from localstorage, it's a string. Localstorage can only store strings. — Kevin B, Jan 28 '15 at 21:04
Oh... Is there any other efficient way to store arrays on someones computer? Or do I have to convert my string to an array and back to a string? — The Man, Jan 28 '15 at 21:05
array to string and then back again. Far easier than it sounds though. — Kevin B, Jan 28 '15 at 21:06
@KevinB Ok. Like the answer below? Will my converted array still have the exact same values though? — The Man, Jan 28 '15 at 21:08
@LcSalazar Strings don't offer a plethora of methods that arrays have. They're array-like but saying they're an array of chars is wrong. — Etheryte, Jan 28 '15 at 21:13
@Nit - True... misspelled... I meant it may also be referenced by indexes — LcSalazar, Jan 28 '15 at 21:16

score 1 · Accepted Answer · edited May 23 '17 at 11:57

1

You need to convert the array to a string if you want to use local storage:

localStorage.setItem("array",JSON.stringify(soldListingArray))

Then when you need to access it later and add items, you convert it back to an array:

soldListingArray = JSON.parse(localStorage.getItem("array"));

This has been answered before; a little research would go a long way: Storing Objects in HTML5 localStorage

edited May 23 '17 at 11:57

Community

1
1

answered Jan 28 '15 at 21:05

Greg Rozmarynowycz

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Would this mess up my array at all? – The Man Jan 28 '15 at 21:10
1

Nope, you can stringify and parse over and over and over and you'll always get the value back exactly as it was before. – Kevin B Jan 28 '15 at 21:10
1

It wouldn't unless there's a problem with your code or how your array is formatted – Greg Rozmarynowycz Jan 28 '15 at 21:10
Alright thanks this should work for me. I didn't know localStorage could only store strings. I used it once before to save integers but I guess that it did the conversion automatically then. Anyway thanks for clearing that up. I'll try out the code later tonight. – The Man Jan 28 '15 at 21:16

Why doesn't my variable save to my array in JavaScript?

1 Answers1