只需将ajv模式从"type": "string"更改为"type": "object"，内置的ajvdate-time格式就可以工作了。
您还可以定义一个自定义的ajv格式来验证Date对象（或字符串），如下所示：

ajv = new Ajv();

ajv.addFormat('custom-date-time', function(dateTimeString) {
  if (typeof dateTimeString === 'object') {
    dateTimeString = dateTimeString.toISOString();
  }

  return !isNaN(Date.parse(dateTimeString));  // any test that returns true/false 
});

...并在ajv模式中调用您的自定义格式，如下所示：

const schema = {
  "properties": {
    "createdAt": {
      "type": "object",
      "format": "custom-date-time"

下面是代码和一个working fiddle for creating a custom date format：

// My example schema

const schema = {
  "properties": {
    "createdAt": {
      "type": "object",
      "format": "custom-date-time"
    },
    "lastName": {
      "type": "string"
    },
    "firstName": {
      "type": "string"
    },
    "required": [ 'createdAt', 'lastName', 'firstName' ],
    "additionalProperties": false,
  }
};

// My example testobject
const testObj = {
  createdAt: new Date(),
  lastName: "Doe",
  firstName: "John"
}

// The validation
ajv = new Ajv();

ajv.addFormat('custom-date-time', function(dateTimeString) {
  if (typeof dateTimeString === 'object') {
    dateTimeString = dateTimeString.toISOString();
  }

  return !isNaN(Date.parse(dateTimeString));  // return true/false 
});

const validate = ajv.compile(schema);
const valid = validate(testObj);

if (valid)
  alert('valid');
else
  alert('Invalid: ' + ajv.errorsText(validate.errors));

有效的方法之一是先转换为JSON Schema兼容的对象。

function makeJsonSchemaCompatible (obj) {
  if (Array.isArray(obj)) {
    return obj.map((subObj) => makeJsonSchemaCompatible(subObj))
  } else if (obj && typeof obj === 'object') {
    const replacement = {}
    const className = obj.constructor.name
    if (className !== 'Object') {
      replacement.__className = className
    }
    Object.entries(obj).map(([k, v]) => { replacement[k] = makeJsonSchemaCompatible(v) })
    return replacement
  }

  return obj
}

不幸的是，format属性不能处理object类型，所以定制格式不是一个选项。然而，我能够添加一个定制关键字（灵感来自于instance关键字，它实际上让你走了一半），给我想要的结果（即值必须是一个Date对象，并且Date必须有效）。

const { equal } = require('assert');
const Ajv = require('ajv');
const { _ } = require('ajv');
const ajv = new Ajv();
const schema = {
  type: 'object',
  properties: {
    jsdate: {
      type: 'object',
      isDate: true,
    },
  },
};

ajv.addKeyword({
  keyword: 'isDate',
  type: 'object',
  code(ctx) {
    const { data } = ctx;
    ctx.pass(_`${data} instanceof Date && !isNaN(+${data})`);
  },
});

const validate = ajv.compile(schema);

equal(validate({ jsdate: new Date() }), true, 'should succeed');

equal(validate({ jsdate: {} }), false, 'should fail for random object');

equal(
  validate({ jsdate: '2001-01-01' }),
  false,
  'should fail for valid date string'
);

equal(
  validate({ jsdate: new Date('rubbish') }),
  false,
  'should fail if Date is invalid'
);

看起来您可以通过使用instanceof关键字（ajv关键字的一部分）来实现预期的结果：。

const Ajv = require("ajv");
const addKeywords = require("ajv-keywords");

const ajv = new Ajv(); // options can be passed, e.g. {allErrors: true}
addKeywords(ajv);

// My example schema
const schema = {
  type: "object",
  properties: {
    createdAt: {
      instanceof: "Date",
    },
    lastName: { type: "string" },
    firstName: { type: "string" },
  },
};

// My example testobject
const testObj = {
  createdAt: new Date(),
  lastName: "Doe",
  firstName: "John",
};

// The validation
const validate = ajv.compile(schema);
const valid = validate(testObj);
if (!valid) console.log("Invalid: " + ajv.errorsText(validate.errors));