Method 1:
document.getElementById("Control ID") .style.visibility="hidden";
document.getElementById("Control ID").style.visibility="visible";
Method 2:
document.getElementById("Control ID").style.display="none";
document.getElementById("Control ID").style.display="inline";
After method one is hidden, the position of the page is still occupied by the control, but the Display similar to the .net verification control is not displayed. =Static
Method 2: The position of the page after hiding is not occupied, similar to Display=Dynamic of .net validation control