//isEqual：判断两个对象是否键值对应相等
functionisEqual(a,b){
//如果a和b本来就全等
if(a===b){
//判断是否为0和-0
returna !== 0 || 1/a ===1/b;
}
//判断是否为null和undefined
if(a==null||b==null){
returna===b;
}
//接下来判断a和b的数据类型
varclassNameA=toString.call(a),
classNameB=toString.call(b);
//如果数据类型不相等，则返回false
if(classNameA !== classNameB){
returnfalse;
}
//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]':
//进行字符串转换比较
return''+ a ===''+ b;
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]':
return+a === +b;
}
//如果是对象类型
if(classNameA == '[object Object]'){
//获取a和b的属性长度
varpropsA = Object.getOwnPropertyNames(a),
propsB = Object.getOwnPropertyNames(b);
if(propsA.length != propsB.length){
returnfalse;
}
for(vari=0;i
varpropName=propsA[i];
//如果对应属性对应值不相等，则返回false
if(a[propName] !== b[propName]){
returnfalse;
}
}
returntrue;
}
//如果是数组类型
if(classNameA == '[object Array]'){
if(a.toString() == b.toString()){
returntrue;
}
returnfalse;
}
}
//test
varobj1={name:"liu",age:22};
varobj2={name:"liu",age:22};
varobj3={name:"liu",age:33};
varstate1=isEqual(obj1,obj2);
varstate2=isEqual(obj1,obj3);
console.log(state1);//true
console.log(state2);//false
varstate3=isEqual(null,undefined);
console.log(state3);//false
varstate4=isEqual(NaN,NaN);
console.log(state4);//true
vararr1=[1,2,3];
vararr2=[1,2,3];
vararr3=[1,23];
varstate5=isEqual(arr1,arr2);
console.log(state5);//true
varstate6=isEqual(arr1,arr3);
console.log(state6);//false
