setter/getter 跨浏览器兼容方案（代码从github摘抄）

完整代码：

    var defineProperty = Object.defineProperty;
    var defineProperties = Object.defineProperties;
    try {
        defineProperty({}, '_', {
            value: 'try'
        })
    } catch (e) {
        if ('__defineGetter__' in {}) {
            defineProperty = function(obj, prop, desc) {
                if ('get' in desc) {
                    obj.__defineGetter__(prop, desc.get)
                }
                if ('set' in desc) {
                    obj.__defineSetter__(prop, desc.set)
                }
            };
            defineProperties = function(obj, props) {
                for (var prop in props) {
                    defineProperty(obj, prop, props[prop])
                }
                return obj
            };
        }
        else if (!defineProperties && window.VBArray) {
            window.execScript([
                'Function vb_global_eval(code)',
                'ExecuteGlobal(code)',
                'End Function'
            ].join('\n'), 'VBScript');

            defineProperties = function(obj, props) {
                var t = setTimeout(function(){});
                var className = 'VBClass' + t;
                var owner = {};
                var buffer = [];
                buffer.push(
                    'Class ' + className,
                    '\tPrivate [__data__], [__proxy__]',
                    '\tPublic Default Function [__const__](d, p)',
                    '\t\tSet [__data__] = d: set [__proxy__] = p',
                    '\t\tSet [__const__] = Me',
                    '\tEnd Function');
                for (var name in props) {
                    owner[name] = true;
                    buffer.push(
                        '\tPublic Property Let [' + name + '](val)',
                        '\t\tCall [__proxy__]([__data__], "' + name + '", val)',
                        '\tEnd Property',
                        '\tPublic Property Set [' + name + '](val)',
                        '\t\tCall [__proxy__]([__data__], "' + name + '", val)',
                        '\tEnd Property',
                        '\tPublic Property Get [' + name + ']',
                        '\tOn Error Resume Next',
                        '\t\tSet[' + name + '] = [__proxy__]([__data__],"' + name + '")',
                        '\tIf Err.Number <> 0 Then',
                        '\t\t[' + name + '] = [__proxy__]([__data__],"' + name + '")',
                        '\tEnd If',
                        '\tOn Error Goto 0',
                        '\tEnd Property')
                }
                buffer.push('End Class');
                buffer.push(
                    'Function ' + className + 'Factory(a, b)',
                    '\tDim o',
                    '\tSet o = (New ' + className + ')(a, b)',
                    '\tSet ' + className + 'Factory = o',
                    'End Function');
                window.vb_global_eval(buffer.join('\r\n'));

                return window[className + 'Factory'](props, function(props,name,value){
                    var fn = props[name];
                    if (arguments.length === 3) {
                        fn.set(value)
                    } else {
                        return fn.get()
                    }
                })
            }
        }
    }

使用范例：

        var data = defineProperties({}, {
            value: {
                get: function() {
                    return 'getter';
                },
                set: function(value) {
                    alert(value);
                }
            }
        });

        alert(data.value);
        data.value = 'test';