javascript - 如何在javascript中保持插入顺序？

Question

这是我的代码生成的格式:

[
    {
        "certifications": [
            {
                "certificate": "NA",
                "completed_on": "2019-09-24T18:30:00.000Z",
                "tc_name": "TC-174195"
            }
        ],
        "firstname": "Dipak",
        "lastname": "Das",
        "email": "dasdipak99@gmail.com"
    }
]

我想设计如下格式:

[
  {
    firstname: "Dipak",
    lastname: "Das",
    email: "dasdipak99@gmail.com",
    certifications: [
      {
        certificate: "NA",
        completed_on: "2019-09-24T18:30:00.000Z",
        tc_name: "TC-174195"
      }
    ]
  }
]

下面是我的代码:

var user = [];
var certificate = {
  certifications: []
};

certificate["firstname"] = rows[0].firstname;
certificate["lastname"] = rows[0].lastname;
certificate["email"] = rows[0].email;

for (let i = 0; i < rows.length; ++i) {
  certificate.certifications.push({
    certificate: rows[i].certification_names,
    completed_on: rows[i].completed_on,
    tc_name: rows[i].tc_name
  });
}

有什么想法如何保持插入顺序吗？我对 javascript 很陌生，如果我没有解释清楚，请道歉。

Answer 1

自 ES6 以来，有人声称该顺序将是

1. 第一个数字不断增加
2. 按插入顺序排列的键

有这个blog post还有这个Stackoverflow thread .

但是你的台词

var certificate = {
  certifications: []
};

将认证作为第一个属性。所以你需要:

var certificate = {};

certificate["firstname"] = "Albert";
certificate["lastname"] = "Lee";
certificate["email"] = "a@b.com";
certificate["certifications"] = [];

certificate.certifications.push({
  certificate: "Java",
  completed_on: "2020/01/02",
  tc_name: "java2020"
});

console.log(certificate);

为了更好地保证订单，请使用Map ，保持按键的原始插入顺序。通常你可能不需要它，但只是出于某种原因如果你想要顺序，并且可以在 for-of 循​​环中拥有这样的顺序:

var certificate = new Map();

certificate.set('firstname', "Albert");
certificate.set('lastname', "Lee");
certificate.set('email', "a@b.com");
certificate.set("certifications", []);
certificate.get("certifications").push({
  "certificate": "Java",
  "completed_on": "2020/01/02",
  "tc_name": "java2020"
})

console.log(certificate);

for (e of certificate) console.log(e)

StackOverflow 不会打印任何内容:

console.log(certificate);

使用 Node 或 Chrome，它是:

Map {
  'firstname' => 'Albert',
  'lastname' => 'Lee',
  'email' => 'a@b.com',
  'certifications' => [
    {
      certificate: 'Java',
      completed_on: '2020/01/02',
      tc_name: 'java2010'
    }
  ]
}