manipulating visibility using js

1  function toggleClock() {
2    // get the clock
3    var myClock = document.getElementById('clock');
4
5    // get the current value of the clock's display property
6    var displaySetting = myClock.style.display;
7
8    // also get the clock button, so we can change what it says
9    var clockButton = document.getElementById('clockButton');
10
11    // now toggle the clock and the button text, depending on current state
12    if (displaySetting == 'block') {
13      // clock is visible. hide it
14      myClock.style.display = 'none';
15      // change button text
16      clockButton.innerHTML = 'Show clock';
17    }
18    else {
19      // clock is hidden. show it
20      myClock.style.display = 'block';
21      // change button text
22      clockButton.innerHTML = 'Hide clock';
23    }
24  }
25