Javascript show element on click

Solution 1:

document.getElementById('showDiv').onclick=function(){
  // Remove any element-specific value, falling back to stylesheets
  document.getElementById('element').style.display='';
};

Solution 2:

It's possible to attach event handlers completely within JavaScript. Example:

document.getElementById('showDiv').onclick = function() {
    // Do whatever now that the user has clicked the link.
};

To reverse the effect of the first line of code you posted, you could use:

document.getElementById('element').style.display = 'block'; // or
document.getElementById('element').style.display = '';