What is the best JavaScript code to create an img element?

Try any of the following for the width of the image you want to create −

myImg.setAttribute('width', '5px');

Or

myImg.width = '5';

Or

myImg.style.width = '5px';

You can also try the following code to add the width and height to the background image −

var myImg = new Image(5,5);
myImg.src = 'http://www.example.com';