jquery源码之神奇的钩子hooks

// 如果不用钩子的情况
// 考生分数以及父亲名
function examinee(name, score, fatherName) {
	return {
		name: name,
		score: score,
		fatherName: fatherName
	};
}

// 审阅考生们
function judge(examinees) {
	var result = {};
	for (var i in examinees) {
		var curExaminee = examinees[i];
		var ret = curExaminee.score;
		// 判断是否有后门关系
		if (curExaminee.fatherName === ‘xijingping‘) {
			ret += 1000;
		} else if (curExaminee.fatherName === ‘ligang‘) {
			ret += 100;
		} else if (curExaminee.fatherName === ‘pengdehuai‘) {
			ret += 50;
		}
		result[curExaminee.name] = ret;
	}
	return result;
}


var lihao = examinee("lihao", 10, ‘ligang‘);
var xida = examinee(‘xida‘, 8, ‘xijinping‘);
var peng = examinee(‘peng‘, 60, ‘pengdehuai‘);
var liaoxiaofeng = examinee(‘liaoxiaofeng‘, 100, ‘liaodaniu‘);

var result = judge([lihao, xida, peng, liaoxiaofeng]);

// 根据分数选取前三名
for (var name in result) {
	console.log("name:" + name);
	console.log("score:" + score);
}

// 这样的话如果我们增加有后台的考生，成本会比较大，需要改动两个地方
// 并且代码块会越来越大，不适合阅读

// 结果根据取决于最终积分
var relationHook = {
	"ligang": 100,
	"xijinping": 1000,
	"pengdehuai": 50
}
// 考生分数以及父亲名
function examinee(name, score, fatherName) {
	return {
		name: name,
		score: score,
		fatherName: fatherName
	};
}

// 审阅考生们
function judge(examinees) {
	var result = {};
	for (var i in examinees) {
		var curExaminee = examinees[i];
		var ret = curExaminee.score;
		if (relationHook[curExaminee.fatherName] ) {
			ret += relationHook[curExaminee.fatherName] ;
		}
		result[curExaminee.name] = ret;
	}
	return result;
}


var lihao = examinee("lihao", 10, ‘ligang‘);
var xida = examinee(‘xida‘, 8, ‘xijinping‘);
var peng = examinee(‘peng‘, 60, ‘pengdehuai‘);
var liaoxiaofeng = examinee(‘liaoxiaofeng‘, 100, ‘liaodaniu‘);

var result = judge([lihao, xida, peng, liaoxiaofeng]);

// 根据分数选取前三名
for (var name in result) {
	console.log("name:" + name);
	console.log("score:" + score);
}

jQuery.extend({
	
	attr: function( elem, name, value, pass ) {
		var ret, hooks, notxml,
			nType = elem.nodeType;

		// don‘t get/set attributes on text, comment and attribute nodes
		if ( !elem || nType === 3 || nType === 8 || nType === 2 ) {
			return;
		}

		if ( pass && jQuery.isFunction( jQuery.fn[ name ] ) ) {
			return jQuery( elem )[ name ]( value );
		}

		// Fallback to prop when attributes are not supported
		if ( typeof elem.getAttribute === "undefined" ) {
			return jQuery.prop( elem, name, value );
		}

		notxml = nType !== 1 || !jQuery.isXMLDoc( elem );

		// All attributes are lowercase
		// Grab necessary hook if one is defined
		if ( notxml ) {
			name = name.toLowerCase();
			// 获取相应的hook, 这里主要是获取  attrHooks,
			hooks = jQuery.attrHooks[ name ] || ( rboolean.test( name ) ? boolHook : nodeHook );
		}
        // 如果value存在，则设置对应属性值为value
		if ( value !== undefined ) {

			// value 为null，则删除该属性
			if ( value === null ) {
				jQuery.removeAttr( elem, name );
				return;
			// 如果hooks存在, 且hooks中有set属性，且不为xml，则执行该set方法，
			// 如果有返回值，则返回该返回值
			} else if ( hooks && "set" in hooks && notxml && (ret = hooks.set( elem, value, name )) !== undefined ) {
				return ret;
			// 处理普通情况的属性赋值
			} else {
				elem.setAttribute( name, value + "" );
				return value;
			}

		// 如果value存在，则取出该属性对应的值	
		// 与上述钩子一样，处理特殊情况
		} else if ( hooks && "get" in hooks && notxml && (ret = hooks.get( elem, name )) !== null ) {
			return ret;
		// 处理普通情况
		} else {
			ret = elem.getAttribute( name );

			// Non-existent attributes return null, we normalize to undefined
			return ret === null ?
				undefined :
				ret;
		}
	}
	// 再来看看钩子的实现
	attrHooks: {
		// 这个钩子只支持type和value
		type: {
			// type 是只有set的
			set: function( elem, value ) {
				// We can‘t allow the type property to be changed (since it causes problems in IE)
				if ( rtype.test( elem.nodeName ) && elem.parentNode ) {
					jQuery.error( "type property can‘t be changed" );
				} else if ( !jQuery.support.radioValue && value === "radio" && jQuery.nodeName(elem, "input") ) {
					// Setting the type on a radio button after the value resets the value in IE6-9
					// Reset value to it‘s default in case type is set after value
					// This is for element creation
					var val = elem.value;
					elem.setAttribute( "type", value );
					if ( val ) {
						elem.value = val;
					}
					return value;
				}
			}
		},
		// Use the value property for back compat
		// Use the nodeHook for button elements in IE6/7 (#1954)
		value: {
			// value
			get: function( elem, name ) {
				if ( nodeHook && jQuery.nodeName( elem, "button" ) ) {
					return nodeHook.get( elem, name );
				}
				return name in elem ?
					elem.value :
					null;
			},
			set: function( elem, value, name ) {
				// 内部实现也有嵌套使用nodeHook钩子
				if ( nodeHook && jQuery.nodeName( elem, "button" ) ) {
					return nodeHook.set( elem, value, name );
				}
				// Does not return so that setAttribute is also used
				elem.value = value;
			}
		}
	},
});