Queue.js To Preload Images Is Waiting Forever? (callback)

I'm using mbostock queue.js script to load several json files, by doing something like that: var q = queue() .defer(d3.json, 'world-110m.json') .defer(d3.tsv, 'world-country-names.

Solution 1:

Here is what queue.js is expecting from the callbacks:

The callbacks follow the Node.js convention where the first argument is an optional error object and the second argument is the result of the task.

Thus a simple version of your code might look like this:

var loadImage = function(src, cb) {
    var img = newImage();
    img.src = src;
    img.onload  = function(){ cb(null, img); };
    img.onerror = function(){ cb('IMAGE ERROR', null); };
};

queue()
    .defer(d3.json, "data/flare.json")
    .defer(d3.csv, "data/test.csv")
    .defer(loadImage, "img/test.png")
    .await( function(error, jsondata, csvdata, imagedata) {
        if (error) { console.log('error', error); } 
        else { console.log('success', jsondata, csvdata, imagedata) }
    });

I'm not sure what (if anything) you wanted to return about the image, but in the above example cb(null, img) I'm returning the whole object.