<INPUT TYPE="button" VALUE="Zoom In" onmouseup="zoomInAndOut('in')">
<INPUT TYPE="button" VALUE="Zoom Out" onmouseup="zoomInAndOut('out')">

function zoomInAndOut(string) {
  if (string == "in") {
    currZoom = container1.style.zoom;
    currZoom = currZoom.substring(0, currZoom.length - 1);
    currZoom = parseInt(currZoom, 10);
    newZoom = currZoom + 1;
	
    if (newZoom > 10000) return;
	
    container1.style.zoom = newZoom + "%";
  }
  else if (string == "out") {
    currZoom = container1.style.zoom;
    currZoom = currZoom.substring(0, currZoom.length - 1);
    currZoom = parseInt(currZoom, 10);
    newZoom = currZoom - 1;
	
	if (newZoom < 1) return;
	
    container1.style.zoom = newZoom + "%";
  }
}

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