HTML5 canvas Image issue

Question

I making a game in HTML5 and this image wont draw. In the chrome js console it says there's nothing wrong with it.

Declaring the image: var wall1 = new Image();

calling the onload:

function render(arg1, arg2, arg3){
    wall1.onload = drawwall(arg1, arg2, arg3);
    wall1.src = "assets/slide.jpg";
}

Draw wall function:

function drawwall(numb, dist, hm){
    ctx.drawImage(wall1,numb*4,4,4,height[hm]*3/dist,numb*4,1,4,height[hm]*3/dist);
}

I've tried return ctx.drawImage(... and return Function(){ctx.drawImage(... but it still wont work.

Answer 1

Change this:

wall1.onload = drawwall(arg1, arg2, arg3);

To this

wall1.onload = function() { drawwall(arg1, arg2, arg3); };

This is necessary because you need to assign a function to the onload property. In the erroneous code you were assigning the result of invoking a function.