export default function isEqual(a, b) {
	//如果a和b本来就全等
	if (a === b) {
		//判断是否为0和-0
		return a !== 0 || 1 / a === 1 / b;
	}
	//判断是否为null和undefined
	if (a == null || b == null) {
		return a === b;
	}
	//接下来判断a和b的数据类型
	var classNameA = toString.call(a),
		classNameB = toString.call(b);
	//var classNameA = typeof(a), (兼容IE的写法)
	//classNameB = typeof(b);
	//如果数据类型不相等，则返回false
	if (classNameA !== classNameB) {
		return false;
	}
	if (a instanceof Date) {
		classNameA = '[object Date]';
	}

	//如果数据类型相等，再根据不同数据类型分别判断
	switch (classNameA) {
		case '[object RegExp]':
		case '[object String]':
		case 'string':
			//进行字符串转换比较
			return '' + a === '' + b;
		case 'number':
		case '[object Number]':
			//进行数字转换比较,判断是否为NaN
			if (+a !== +a) {
				return +b !== +b;
			}
			//判断是否为0或-0
			return +a === 0 ? 1 / +a === 1 / b : +a === +b;
		case '[object Date]':
		case '[object Boolean]':
		case 'boolean':
			return +a === +b;
	}
	//如果是对象类型
	if (classNameA == '[object Object]' || classNameA == 'object') {
		//获取a和b的属性长度
		var propsA = Object.getOwnPropertyNames(a),
			propsB = Object.getOwnPropertyNames(b);
		if (propsA.length != propsB.length) {
			return false;
		}
		for (var i = 0; i < propsA.length; i++) {
			var propName = propsA[i];
			//如果对应属性对应值不相等，则返回false
			if (a[propName] !== b[propName]) {
				return false;
			}
		}
		return true;
	}
	//如果是数组类型
	if (classNameA == '[object Array]') {
		if (a.toString() == b.toString()) {
			return true;
		}
		return false;
	}
}