How to give a unique “id” for each canvas?

Question

Canvas is new to me - so I need help.

I have a function that draws data retrieved using getImageData () - on an existing canvas or newly created.

I need to make it possible for a newly created canvas to give it a unique id. However, when I try the following - the canvas is created but the id is undefined.

function drawImageData(img, t1, t2, cc, scale, targetCanvas, userId) {
var canvas = targetCanvas || document.createElement('canvas');
if(!targetCanvas){
    canvas.setAttribute('id', userId); 

   // the rest of the code
   }

How to properly assign userId - to "id" canvas?

Answer 1

Your code seems to be working fine.

jsfiddle.net/qsekzt9x/

@gurvinder372 is right about the if condition in his answer below