Why is JavaScript passing into a parameter the source code text?

Question

Console log:

   [Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object]
     (index):104

   function (newFeedItems) {
       console.log(feedItems);
   } (index):113

   Uncaught TypeError: Object function (newFeedItems) {
      console.log(feedItems);
   } has no method 'sort'

Where is it getting this from?

function (newFeedItems) {
    console.log(feedItems);
} (index):113

when it's supposed to be:

[Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object]

Take a look at the functions fetchFeeds() and processLatestFeed(). The problem starts at processLatestFeed(function(newFeedItems) {

function fetchFeeds() {
    fetchVideos(function(newVideoItems) {
        fetchPodcasts(function(newPodcastItems) {
            var newFeedItems = newVideoItems.concat(newPodcastItems);
            console.log(newFeedItems);
            processLatestFeed(function(newFeedItems) {
                console.log(feedItems);
            });
        });
    });
}

function processLatestFeed(newFeedItems, callback) {
    console.log(newFeedItems);
    newFeedItems.sort(function(a,b) {return (a.date > b.date) ? -1 : ((b.date > a.date) ? 1 : 0);});

    for (i in newFeedItems) {
        var newItem = newFeedItems[i];

        if (!isItemInFeed(newItem)) {
            feedItems.push(newItem);
        }

        if (feedItems.length == 50) {
            break;   
        }
    }

    callback();
}

Can you describe your questions further please? I don't think I understand properly what you're trying to say — Zach Saucier
– Zach Saucier, Commented Feb 23, 2014 at 3:03
@ZachSaucier see newFeedItems and how it is logged to the console, you can see how it correctly displays that it's an array of objects [Object, Object, Object....] however when newFeedItems get passed into processLatestFeed(function(newFeedItems)... it doesn't seem to pass in as an array of object but as source code itself (see the second part of the console log). — Jonathan
– Jonathan, Commented Feb 23, 2014 at 3:06
Not sure If I understood, but change this: processLatestFeed(newFeedItems, function(){ console.log(feedItems); }); — juvian
– juvian, Commented Feb 23, 2014 at 3:11

Felix Kling · Accepted Answer · 2014-02-23 03:13:48Z

1

You are passing a function as first argument to processLatestFeed:

processLatestFeed(function(newFeedItems) {
  console.log(feedItems);
});

but you defined that function to accept an array as first argument and the callback as second argument:

function processLatestFeed(newFeedItems, callback) {
    console.log(newFeedItems); // <- this logs the function source
    // ...
}

So you have to call the function as

processLatestFeed(newFeedItems, function() {
  // you are not passing an arguments to the callback
});

answered Feb 23, 2014 at 3:13

Felix Kling

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2 Comments

Jonathan Over a year ago

im an idiot! been playing around with JavaScript all day - think this my cue to take a break :)

Felix Kling Over a year ago

Yep, that often helps :)

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