Passing anonymous functions as parameters for later use

Question

I'm having issues with a script that I made for use in HTML5. Here is the function

function loadImage(loc,after,para){
        var img = new Image();
        img.src = loc;
        if(typeof(after) != "undefined" && typeof(para) != "undefined"){
            img.onloadeddata  = after(img,para);
        }else if(typeof(after) != "undefined"){
            img.onloadeddata  = after(img);
        }
        return img;
}

and here is what is calling it

window.globalFriends[i][2]=loadImage('http://graph.facebook.com/'+window.globalFriends[i][0]+'/picture', function (a){
    updateLoaders();
    loadingDrawPerson(a);});

What I'm trying to do is send a function as a parameter for it then to be called. It kinda of works but it a weird way. For example; All the images do get loaded but the onloadeddata either fires the function way to early or the function is getting executed before it gets to the loadImage function.

What are your ideas on my malfunctioning script?

Thank-you for reading Paul

typeof is an operator, not a function so there is no need for a grouping operator after it. Use: typeof after — RobG
– RobG, Commented May 16, 2011 at 23:36

Jacob · Accepted Answer · 2011-05-16 23:57:29Z

3

A line like this:

img.onloadeddata  = after(img,para);

Means "call the after function with arguments img and para" and assign the result to onloadeddata." If, instead, you're wanting to assign the function to onloadeddata, do this:

img.onloadeddata = function() { after(img, para); };

edited May 16, 2011 at 23:57

answered May 16, 2011 at 23:06

Jacob

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Comments

Raynos · Accepted Answer · 2011-05-16 23:04:05Z

1

It's img.onload And it needs a function.

Try

img.onload = function() {
    after(img, para);
}

I think your missing the para parameter

window.globalFriends[i][2]=loadImage('http://graph.facebook.com/'+window.globalFriends[i][0]+'/picture', function (a){
    updateLoaders();
    loadingDrawPerson(a);}/*, para */); // <- where is para?

answered May 16, 2011 at 23:04

Raynos

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