Javascript check if array filled from function

Question

I have this function

offer.getReceivedItems(function(err, items) {

It returns an array (items) or throws an error err if it failed. Many times, when there isn't an err, the items array is empty. Like

[]

But when this array is empty, I need to try the same function again

offer.getReceivedItems(function(err, items) {

but how I can go back to it, when items is empty...

I tried so much, but I cannot find it...

Code looks like

offer.getReceivedItems(function(err, items) {
        if (err) {
            console.log("Couldn't get received items: " + err);
            offer.decline();
        } else {
            console.log(items);
            items.forEach(function(item,i,arr){
            ....

The forEach doesn't run when there is an empty array...

items.length will be zero if there is nothing in the array. — VLAZ
– VLAZ, Commented Nov 3, 2016 at 20:37
@vlaz that i know. But how i can "restart" that he trying this function again... i can make if(items.length > 0) but how i can make that he do offer.getReceivedItems again? — Scholli
– Scholli, Commented Nov 3, 2016 at 20:38
Make it recursive by calling offer.getReceivedItems again in the else. Or, better yet, use Promises with resolve and reject. — Scott Marcus
– Scott Marcus, Commented Nov 3, 2016 at 20:39
@ScottMarcus can you show me an example? i am not so good in javascript — Scholli
– Scholli, Commented Nov 3, 2016 at 20:40
See multiple, sequential fetch() Promise . When should process conclude? — guest271314
– guest271314, Commented Nov 3, 2016 at 20:41

Community · Accepted Answer · 2017-05-23 10:32:42Z

1

You should check if the array is empty before iterating with forEach. Check items.length.

There is a much longer, detailed explanation in this StackOverflow answer.

edited May 23, 2017 at 10:32

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answered Nov 3, 2016 at 20:40

user2441511

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4 Comments

Scholli Over a year ago

I know that with the checking of length, but how i can restart from beginning, if the length is zero?... that is my problem :/

user2441511 Over a year ago

What function is offer.getReceivedItems inside of? (E.g., if it's called tryItems, like so: function tryItems(args) { offer.getRecievedItems ... }) You can recursively call that external function inside the else of your code snippet, like was suggested by Scott Marcus in a comment above, e.g. else { if (items.length === 0) { tryItems(args); } ... }

Scholli Over a year ago

that i know... but how i can get back to the start?... @teroi that he trys again

teroi Over a year ago

What do you mean by "back to the start"?

vbguyny · Accepted Answer · 2016-11-03 20:43:00Z

1

I am having trouble understanding what it is you are trying to do but does the following help you?

var callBack = function(err, items) {
        if (err) {
            console.log("Couldn't get received items: " + err);
            offer.decline();
            offer.getReceivedItems(callBack); // Call again
        } else {
            console.log(items);
            items.forEach(function(item,i,arr){
            ....
        }
    };

// Original call
offer.getReceivedItems(callBack);

answered Nov 3, 2016 at 20:43

vbguyny

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