Javascript change Div style

Question

I want that part 1 onclick div style changes and part 2 again on click it comes back to normal. I tried doing so but I failed to achieve the

Answer 1

Better change the class of the element (.regular is black, .alert is red):

function abc(){
  var myDiv = document.getElementById("test");
  if (myDiv.className == 'alert') {
    myDiv.className = 'regular';
  } else {
    myDiv.className = 'alert';
  }
}