Javascript loop through array of objects

Question

I'm trying to loop through an array and it keeps saying length is 0

Screenshot of array:

I've tried for(key in results)... and for( var i = 0; i < length... But both don't run anything inside the loop: console.log(results[i]); // Or key if it's a key in loop

I'm sure it's a rookie mistake, can anyone spot it?

The code I'm using:

    var store = new Lawnchair({name: 'testing'}, function (store) {

        // Create an object
        var me = {key: 'Jordy', age: 19, date_of_birth: "1233-09-06"};
        var mee = {key: 'dude', age: 17, date_of_birth: "2222-09-06"};
        var meee = {key: 'gast', age: 8, date_of_birth: "5555-09-06"};

        // Save it
        store.save(me);
        store.save(mee);
        store.save(meee);

//         Access it later... Yes even after a page refresh!
        store.where('record.age < 20', function (records) {
            var html = "";
            var list = document.getElementById('people');
//            for (var i = 0; i < records.length; i++) {
//                var record = records[i];
//                html += "<li>" + record.key + " is " + record.age + " years old and was born on " + record.date_of_birth + "</li>";
//            }

            for(var key in records){
                console.log("SD");
            }

            console.log(records);
            list.innerHTML = html;

        });
    });

When I console.log(records) as seen above the result is the screenshot. When I loop over it nothing happens because records.length === 0

Edit:

store.where('record.age < 20', function(records){
        console.log(records); // Array with property length 3
        console.log(records.length); // 0
    });

The first console.log shows the array with records.length === 3 but the second console.log shows 0. How?

Looks like this could be an issue with asynchronity. Where do you get the array from? — Dylan Meeus
– Dylan Meeus, Commented Aug 9, 2016 at 10:13
yeah where do you get length from... it seems like an arbitrary variable. for ... loop should be sufficient, could you show some code though, because we can't see anything — Callum Linington
– Callum Linington, Commented Aug 9, 2016 at 10:15
your problem is not with loop. your array is empty when you want to reach it. show us more code. — Doruk
– Doruk, Commented Aug 9, 2016 at 10:17

IronAces · Accepted Answer · 2016-08-09 10:15:46Z

1

Without providing code, it's difficult to say if you've made a rookie mistake! I see that you're using length rather than arrayName.length? I don't know the name of your array...

for (var i = 0; i < array.length;i++){
    //logic here
    };

answered Aug 9, 2016 at 10:15

IronAces

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1 Comment

IronAces Over a year ago

Can you edit your post with code that you are trying @g3mini?

rasmusvhansen · Accepted Answer · 2016-08-09 10:31:51Z

0

To iterate an array and produce side effects, use https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach

E.g

[1,2,3,4].forEach(num => console.log(num));

If on the other hand you need to filter or transform the array, consider using filter, map or reduce instead. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

answered Aug 9, 2016 at 10:31

rasmusvhansen

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