JavaScript中模拟assert函数与if嵌套判断详解

function assert(condition, message = 'Assertion failed') {  
    if (!condition) {  
        throw new Error(message);  
    }  
}
```

function checkUserQualifications(user) {  
    // 假设user对象包含age, profession, hasSignedAgreement属性  
      
    // 检查年龄是否大于等于18  
    assert(user.age >= 18, 'User must be at least 18 years old.');  
  
    // 进一步的检查，根据职业  
    if (user.profession === 'teacher') {  
        // 教师有特殊的资格要求  
        assert(user.hasSpecialTeacherQualification, 'Teachers must have special qualification.');  
    } else if (user.profession === 'doctor') {  
        // 医生需要医学执照  
        assert(user.hasMedicalLicense, 'Doctors must have a medical license.');  
    } else {  
        // 其他职业，确保签署了协议  
        assert(user.hasSignedAgreement, 'All users must sign the agreement.');  
    }  
  
    // 如果所有检查都通过，执行某些操作  
    console.log('User qualifications are met. Proceeding with the operation.');  
}  
  
// 示例用户数据  
const user1 = {  
    age: 25,  
    profession: 'teacher',  
    hasSpecialTeacherQualification: true,  
    hasSignedAgreement: true  
};  
  
const user2 = {  
    age: 30,  
    profession: 'doctor',  
    hasMedicalLicense: false, // 故意设置为false以触发断言错误  
    hasSignedAgreement: true  
};  
  
// 测试user1  
try {  
    checkUserQualifications(user1);  
} catch (error) {  
    console.error(error.message);  
}  
  
// 测试user2  
try {  
    checkUserQualifications(user2);  
} catch (error) {  
    console.error(error.message); // 应输出：Doctors must have a medical license.  
}
```