適配器模式 將一個(gè)對(duì)象或者類(lèi)的接口翻譯成某個(gè)指定的系統(tǒng)可以使用的另外一個(gè)接口。

適配器基本上允許本來(lái)由于接口不兼容而不能一起正常工作的對(duì)象或者類(lèi)能夠在一起工作.適配器將對(duì)它接口的調(diào)用翻譯成對(duì)原始接口的調(diào)用，而實(shí)現(xiàn)這樣功能的代碼通常是最簡(jiǎn)的。

我們可能已經(jīng)用過(guò)的一個(gè)適配器的例子就是jQuery的jQuery.fn.css()方法，這個(gè)方法幫助規(guī)范了不同瀏覽器之間樣式的應(yīng)用方式，使我們使用簡(jiǎn)單的語(yǔ)法，這些語(yǔ)法被適配成為瀏覽器背后真正支持的語(yǔ)法：

// Cross browser opacity:
// opacity: 0.9;  Chrome 4+, FF2+, Saf3.1+, Opera 9+, IE9, iOS 3.2+, Android 2.1+
// filter: alpha(opacity=90);  IE6-IE8

// Setting opacity
$( ".container" ).css( { opacity: .5 } );

// Getting opacity
var currentOpacity = $( ".container" ).css('opacity');

將上面的代碼變得可行的相應(yīng)的jQuery核心css鉤子在下面：

get: function( elem, computed ) {
  // IE uses filters for opacity
  return ropacity.test( (
        computed && elem.currentStyle ?
            elem.currentStyle.filter : elem.style.filter) || "" ) ?
    ( parseFloat( RegExp.$1 ) / 100 ) + "" :
    computed ? "1" : "";
},

set: function( elem, value ) {
  var style = elem.style,
    currentStyle = elem.currentStyle,
    opacity = jQuery.isNumeric( value ) ?
          "alpha(opacity=" + value * 100 + ")" : "",
    filter = currentStyle && currentStyle.filter || style.filter || "";

  // IE has trouble with opacity if it does not have layout
  // Force it by setting the zoom level
  style.zoom = 1;

  // if setting opacity to 1, and no other filters
  //exist - attempt to remove filter attribute #6652
  if ( value >= 1 && jQuery.trim( filter.replace( ralpha, "" ) ) === "" ) {

    // Setting style.filter to null, "" & " " still leave
    // "filter:" in the cssText if "filter:" is present at all,
    // clearType is disabled, we want to avoid this style.removeAttribute
    // is IE Only, but so apparently is this code path...
    style.removeAttribute( "filter" );

    // if there there is no filter style applied in a css rule, we are done
    if ( currentStyle && !currentStyle.filter ) {
      return;
    }
  }

  // otherwise, set new filter values
  style.filter = ralpha.test( filter ) ?
    filter.replace( ralpha, opacity ) :
    filter + " " + opacity;
}
};