function getWindowWidth() {
  return window.innerWidth ||
         document.documentElement && document.documentElement.clientWidth ||
         document.body && document.body.clientWidth ||
         0;
}
System variable that stores the height of the drawing canvas. This value
is set by the second parameter of the createCanvas() function. For
example, the function call createCanvas(320, 240) sets the height
variable to the value 240. The value of height defaults to 100 if
createCanvas() is not used in a program.

@property {Number} height
@readOnly