/**

* @author nikai (@胖嘟嘟的骨头, nikai@baidu.com)

* 一些常用的方法库

*/

var util = {

isPlainObject: function (obj) {

var key;

var class2type = {};

var hasOwn = class2type.hasOwnProperty;

// Must be an Object.

// Because of IE, we also have to check the presence of the constructor property.

// Make sure that DOM nodes and window objects don't pass through, as well

if (!obj || typeof obj !== 'object' || obj.nodeType) {

return false;

}

// Not own constructor property must be Object

var hasNoOwn = !hasOwn.call(obj, 'constructor');

var hasNoOwnPrototypeOf = !hasOwn.call(obj.constructor.prototype, 'isPrototypeOf');

if (obj.constructor && hasNoOwn && hasNoOwnPrototypeOf) {

return false;

}

// Own properties are enumerated firstly, so to speed up,

// if last one is own, then all properties are own.

for (key in obj) {}

return key === undefined || hasOwn.call(obj, key);

},

/**

* 深度扩展一个对象

*/

extend: function (destination, source) {

var i,

toStr = Object.prototype.toString,

astr = '[object Array]';

destination = destination || {};

for (i in source) {

if (source.hasOwnProperty(i)) {

if (util.isPlainObject(source[i])) {

destination[i] = (toStr.call(source[i]) === astr) ? [] : {};

arguments.callee(destination[i], source[i]);

destination[i] = source[i];

} else {

destination[i] = source[i];

}

}

}

return destination;

},

/**

* copy an object

* @param {Object} obj the obj

* @return {Object} new object

*/

copy: function (obj) {

return this.extend({}, obj);

},

/**

* 为类型构造器建立继承关系

* @name baidu.lang.inherits

* @function

* @grammar baidu.lang.inherits(subClass, superClass[, className])

* @param {Function} subClass 子类构造器

* @param {Function} superClass 父类构造器

* @remark

*

使subClass继承superClass的prototype，因此subClass的实例能够使用superClass的prototype中定义的所有属性和方法。<br>

这个函数实际上是建立了subClass和superClass的原型链集成，并对subClass进行了constructor修正。<br>

<strong>注意：如果要继承构造函数，需要在subClass里面call一下，具体见下面的demo例子</strong>

* @shortcut inherits

* @meta standard

*/

inherits: function (subClass, superClass) {

var key;

var proto;

var selfProps = subClass.prototype;

var Clazz = new Function();

Clazz.prototype = superClass.prototype;

proto = subClass.prototype = new Clazz();

for (key in selfProps) {

proto[key] = selfProps[key];

}

subClass.prototype.constructor = subClass;

subClass.superClass = superClass.prototype;

},

// 在页面中添加样式

addCssByStyle: function (cssString) {

var doc = document;

var style = doc.createElement('style');

style.setAttribute('type', 'text/css');

if (style.styleSheet) { // IE

style.styleSheet.cssText = cssString;

} else { // w3c

var cssText = doc.createTextNode(cssString);

style.appendChild(cssText);

}

var heads = doc.getElementsByTagName('head');

if (heads.length) {

heads[0].appendChild(style);

} else {

doc.documentElement.appendChild(style);

}

}

}