visibility.js

HTMLElement.prototype.show = function() {
  this.style.display = ''
}
HTMLElement.prototype.hide = function() {
  this.style.display = 'none'
}
HTMLElement.prototype.toggle = function(bool) {
  this.style.display = bool ? '' : 'none'
}
HTMLElement.prototype.visible = function() {
  return this.style.display !== 'none'
}

// usage: $('.foo').hide()
// usage: $('.foo').show()
// usage: $('.foo').toggle(false) // hide
// usage: $('.foo').visible() // false