[浅写深度比较isEqual]

function isEqual(obj1,obj2) {
    // 如果有一个不是对象，直接对比
    if(!(typeof obj1 === 'object' && typeof obj1 !==null) || !(typeof obj2 === 'object' && typeof obj2 !==null)) {
        return obj1 === obj2;
    }
    if(obj1 === obj2) {
        return true;
    }
    const obj1Keys = Object.keys(obj1);
    const obj2Keys = Object.keys(obj1);
    if(obj1Keys.length !== obj2Keys.length) {
        return false;
    }
    for(let key in obj1) {
        const res = isEqual(obj1[key],obj2[key]); // 递归比较
        if(!res) {
            return false;
        }
    }
    return true;
}