使用jQuery制作Web页面遮罩层插件的实例教程

$.fn.extend({ 
  /** 
   * 给元素添加遮罩层 
   * @param message {String} [可选]遮罩层显示内容 
   */ 
  mask: function (message) { 
    var $target = this, 
      fixed = false, 
      targetStatic = true; 
 
    if (Object.prototype.toString.call(message) !== '[object String]' || !message) { 
      //如果message为空或者不是字符串，则用默认的消息提示。 
      message = '请稍候。。。'; 
    } 
 
    if ($target.length === 0) { 
      $target = $('body'); 
    } else { 
      if ($target.length > 1) { 
        $target = $target.first(); 
      } 
 
      if ($target[0] === window || $target[0] === document) { 
        $target = $('body'); 
      } 
    } 
     
    if($target[0] === document.body){ 
      fixed = true; 
    } 
 
    //如果目标元素已经有遮罩层，获取遮罩层 
    var old = $target.data('rhui.mask'); 
    if (old) { 
      old.$content.html(message); 
      center($target, old.$content, fixed); 
      return; 
    } 
 
    //如果被遮盖的元素是static，把元素改成relative 
    if ($target.css('position') === 'static') { 
      targetStatic = true; 
      $target.css('position', 'relative'); 
    } 
 
    var $content, $overlay; 
    if (fixed) { 
      $overlay = $('
'); 
      $cOntent= $('
' + message + '
'); 
    } else { 
      $overlay = $('
'); 
      $cOntent= $('
' + message + '
'); 
    } 
 
    $overlay.appendTo($target); 
    $content.appendTo($target); 
 
    //显示遮罩层 
    $overlay.show(); 
    $content.show(); 
 
    //让遮罩层居中 
    center($target, $content, fixed); 
 
    //把遮罩层信息添加到$target 
    $target.data('rhui.mask', { 
      fixed: fixed, 
      $overlay: $overlay, 
      $content: $content, 
      targetStatic: targetStatic 
    }); 
 
    /** 
     * 让遮罩层内容居中显示 
     * @param $target  被遮盖的元素 
     * @param $content 遮罩层内容元素 
     * @param fixed   遮罩层是否固定显示 
     */ 
    function center($target, $content, fixed) { 
      var $window, 
        height = $content.outerHeight(true), 
        width = $content.outerWidth(true); 
 
      if (fixed) { 
        //如果遮罩层固定显示，让遮罩层在window居中 
        $window = $(window); 
        $content.css({ 
          left: ($window.width() - width) / 2, 
          top: ($window.height() - height) / 2 
        }); 
      } else { 
        //让遮罩层在$target中居中 
        $content.css({ 
          left: ($target.width() - width) / 2, 
          top: ($target.height() - height) / 2 
        }); 
      } 
    } 
  }, 
 
  /** 
   * 取消遮罩层 
   */ 
  unmask: function () { 
    var $target; 
 
    if (this.length === 0) { 
      $target = $('body'); 
    } else { 
      $target = this.first(); 
      if ($target[0] === window || $target[0] === document) { 
        $target = $('body'); 
      } 
    } 
 
    var data = $target.data('rhui.mask'); 
    if (!data) { 
      return; 
    } 
 
    //还原目标元素的position属性 
    if (data.targetStatic) { 
      $target.css('position', 'static'); 
    } 
 
    data.$overlay.remove(); 
    data.$content.remove(); 
 
    $target.removeData('rhui.mask'); 
  } 
}); 

/* 遮罩层样式 */ 
.rhui-mask { 
  position: absolute; 
  top: 0; 
  right: 0; 
  bottom: 0; 
  left: 0; 
  z-index: 9000; 
  display: block; 
  margin: 0; 
  padding: 0; 
  border-style: none; 
  background-color: #777; 
  opacity: 0.3; 
  zoom: 1; 
  filter: alpha(opacity=30); 
} 
 
/* 遮罩层显示内容样式 */ 
.rhui-mask-content { 
  position: absolute; 
  z-index: 9999; 
  display: block; 
  margin: 0; 
  padding: 15px 20px; 
  border: 2px solid rgb(109, 157, 215); 
  background-color: #fff; 
  color: blue; 
  letter-spacing: 2px; 
  font-weight: bold; 
  font-size: 15px; 
  cursor: wait; 
}