Trying to push into array, but it stays empty

Question

I'm trying to push info into array, but the array comes out as empty. What am I doing wrong?

function fixItems(items){
    var fixeditems = [];
    fs.readFile('prices.json', 'utf8', function(err, data){
        if(err){}
        var jason = JSON.parse(data);
        for(var k = 0; k < jason.prices.length; k++){
            for(var i = 0; i < items.itemsToReceive.length; i++){
                fixeditems.push({
                    name: items.itemsToReceive[i].market_hash_name,
                    classid: items.itemsToReceive[i].classid
                });
            }
        }
    });
    return fixeditems;
}

The push itself seems fine. Your problem is probably the loops. Either `json.prices` is empty or `items.itemsToReceive` is.. — Chris, Mar 11 '17 at 21:11
I have a strong feeling that you should have used [`fs.readFileSync`](https://nodejs.org/api/fs.html#fs_fs_readfilesync_file_options). The very fact that `fs.readFile` expects a function of (error, data) as the last argument is a sign it's asynchronous. — rishat, Mar 11 '17 at 21:16
Switch to [fs.readFileSync()](https://nodejs.org/api/fs.html#fs_fs_readfilesync_file_options) — NotBad4U, Mar 11 '17 at 21:16
Thanks to them who gave a suggestion to switch to `fs.readFileSync` — James Aniszt, Mar 11 '17 at 21:20
As a general rule, switching to `fs.readFileSync` is **not** the best solution. Node is asynchronous for a reason. If you use synchronous reads, the entire server will block until the reading is complete. — , Mar 12 '17 at 05:09
*How is it asynchronous call?* It is an asynchronous call because `fs.readFile` is by nature asynchronous. — , Mar 12 '17 at 05:10

score 0 · Answer 1 · answered Mar 11 '17 at 22:48

It's an async call, so your variable is returned before it is filled up. Actually you could go like this, if being async is not a priority:

function fixItems(items){ 
    let fixeditems = [];
    let data = fs.readFileSync('prices.json', 'utf8')
    let jason = JSON.parse(data); 
    for(var k = 0; k < jason.prices.length; k++){ 
        for(var i = 0; i < items.itemsToReceive.length; i++){ 
            fixeditems.push({ 
                name: items.itemsToReceive[i].market_hash_name,
                 classid: items.itemsToReceive[i].classid 
             }); 
         }
    }
}

Otherwise you can wrap everything in a Promise or use libraries such as Async to perform these kind of tasks.

Trying to push into array, but it stays empty

1 Answers1