Optional options: MongoClientOptionsStatic Readonly captureStatic captureSets or gets the default captureRejection value for all emitters.设置或获取所有发射器的默认captureRejection值。
Static defaultStatic Readonly errorThis symbol shall be used to install a listener for only monitoring 此符号应用于安装仅用于监视'error' events. Listeners installed using this symbol are called before the regular 'error' listeners are called.'error'事件的侦听器。在调用常规'error'侦听器之前，将调用使用此符号安装的侦听器。
Installing a listener using this symbol does not change the behavior once an 一旦发出'error' event is emitted, therefore the process will still crash if no regular 'error' listener is installed.'error'事件，使用此符号安装侦听器不会改变行为，因此，如果未安装常规的'error'侦听器，进程仍将崩溃。
Connect to MongoDB using a url使用url连接到MongoDB
Create a new Db instance sharing the current socket connections.创建一个共享当前套接字连接的新Db实例。
Optional dbName: stringThe name of the database we want to use. If not provided, use database name from connection string.我们要使用的数据库的名称。如果未提供，请使用连接字符串中的数据库名称。
Optional options: DbOptionsOptional settings for Db constructionDb构造的可选设置
Rest ...args: Parameters<MongoClientEvents[EventKey]>Optional event: string | symbol | EventKeyCreates a new ClientSession. 创建新的ClientSession。When using the returned session in an operation a corresponding ServerSession will be created.在操作中使用返回的会话时，将创建相应的ServerSession。
Optional options: ClientSessionOptionsA ClientSession instance may only be passed to operations being performed on the same MongoClient it was started from.ClientSession实例只能传递给在启动它的同一MongoClient上执行的操作。
Create a new Change Stream, watching for new changes (insertions, updates, replacements, deletions, and invalidations) in this cluster. 创建一个新的变更流，监视此群集中的新变更（插入、更新、替换、删除和无效）。Will ignore all changes to system collections, as well as the local, admin, and config databases.将忽略对系统集合以及本地、管理和配置数据库的所有更改。
Type of the data being detected by the change stream变更流检测到的数据类型
Type of the whole change stream document emitted发出的整个变更流文档的类型
An array of pipeline stages through which to pass change stream documents. This allows for filtering (using $match) and manipulating the change stream documents.一组管道阶段，通过这些阶段传递更改流文档。这允许筛选（使用$match）和操作变更流文档。
Optional settings for the command命令的可选设置
watch() accepts two generic arguments for distinct use cases:watch()为不同的用例接受两个泛型参数：
A convenience method for creating and handling the clean up of a ClientSession.创建和处理ClientSession清理的一种方便方法。The session will always be ended when the executor finishes.会话将始终在executor完成时结束。
An executor function that all operations using the provided session must be invoked in必须在中调用使用所提供会话的所有操作的执行器函数
Static connectConnect to MongoDB using a url使用url连接到MongoDB
Optional options: MongoClientOptionsThe programmatically provided options take precedence over the URI options.以编程方式提供的选项优先于URI选项。
Static getReturns a copy of the array of listeners for the event named 返回名为eventName.eventName的事件的侦听器数组的副本。
For 对于EventEmitters this behaves exactly the same as calling .listeners on the emitter.EventEmitter，其行为与在发射器上调用侦听器完全相同。
For 对于EventTargets this is the only way to get the event listeners for the event target. This is useful for debugging and diagnostic purposes.EventTarget，这是获取事件目标的事件侦听器的唯一方法。这对于调试和诊断非常有用。
import { getEventListeners, EventEmitter } from 'node:events';
{
const ee = new EventEmitter();
const listener = () => console.log('Events are fun');
ee.on('foo', listener);
console.log(getEventListeners(ee, 'foo')); // [ [Function: listener] ]
}
{
const et = new EventTarget();
const listener = () => console.log('Events are fun');
et.addEventListener('foo', listener);
console.log(getEventListeners(et, 'foo')); // [ [Function: listener] ]
}
v15.2.0, v14.17.0
Static listenerA class method that returns the number of listeners for the given 一个类方法，用于返回在给定eventName registered on the given emitter.emitter上注册的给定eventName的侦听器数。
import { EventEmitter, listenerCount } from 'node:events';
const myEmitter = new EventEmitter();
myEmitter.on('event', () => {});
myEmitter.on('event', () => {});
console.log(listenerCount(myEmitter, 'event'));
// Prints: 2
The emitter to query要查询的发射器
The event name事件名称
v0.9.12
Since v3.2.0 - Use 由于v3.2.0-请改用listenerCount instead.listenerCount。
Static onimport { on, EventEmitter } from 'node:events';
import process from 'node:process';
const ee = new EventEmitter();
// Emit later on
process.nextTick(() => {
ee.emit('foo', 'bar');
ee.emit('foo', 42);
});
for await (const event of on(ee, 'foo')) {
// The execution of this inner block is synchronous and it processes one event at a time (even with await). 这个内部块的执行是同步的，它一次处理一个事件（即使有等待）。
// Do not use if concurrent execution is required.如果需要并发执行，请不要使用。
console.log(event); // prints ['bar'] [42]
}
// Unreachable here
Returns an 返回一个迭代AsyncIterator that iterates eventName events. eventName事件的AsyncIterator。It will throw if the 如果EventEmitter emits 'error'. EventEmitter发出'error'，它将抛出。It removes all listeners when exiting the loop. 它在退出循环时删除所有侦听器。The 每次迭代返回的value returned by each iteration is an array composed of the emitted event arguments.value是一个由发出的事件参数组成的数组。
An AbortSignal can be used to cancel waiting on events:AbortSignal可用于取消等待事件：
import { on, EventEmitter } from 'node:events';
import process from 'node:process';
const ac = new AbortController();
(async () => {
const ee = new EventEmitter();
// Emit later on
process.nextTick(() => {
ee.emit('foo', 'bar');
ee.emit('foo', 42);
});
for await (const event of on(ee, 'foo', { signal: ac.signal })) {
// The execution of this inner block is synchronous and it processes one event at a time (even with await). 这个内部块的执行是同步的，它一次处理一个事件（即使有等待）。
// Do not use if concurrent execution is required.如果需要并发执行，请不要使用。
console.log(event); // prints ['bar'] [42]
}
// Unreachable here
})();
process.nextTick(() => ac.abort());
The name of the event being listened for正在侦听的事件的名称
Optional options: StaticEventEmitterOptionsthat iterates 迭代eventName events emitted by the emitteremitter发出的eventName事件
v13.6.0, v12.16.0
Static onceCreates a 创建一个Promise that is fulfilled when the EventEmitter emits the given event or that is rejected if the EventEmitter emits 'error' while waiting.Promise，该Promise在EventEmitter发出给定事件时实现，或者如果EventEmitter在等待时发出'error'则被拒绝。
The Promise will resolve with an array of all the arguments emitted to the given event.Promise将通过向给定事件发出的所有参数的数组进行解析。
This method is intentionally generic and works with the web platform EventTarget interface, which has no special 此方法是有意通用的，可与web平台EventTarget接口配合使用，该接口没有特殊的'error' event semantics and does not listen to the 'error' event.'error'事件语义，也不侦听'error'消息。
import { once, EventEmitter } from 'node:events';
import process from 'node:process';
const ee = new EventEmitter();
process.nextTick(() => {
ee.emit('myevent', 42);
});
const [value] = await once(ee, 'myevent');
console.log(value);
const err = new Error('kaboom');
process.nextTick(() => {
ee.emit('error', err);
});
try {
await once(ee, 'myevent');
} catch (err) {
console.error('error happened', err);
}
The special handling of the 'error' event is only used when events.once() is used to wait for another event. 'error'事件的特殊处理仅在events.once()用于等待另一个事件时使用。If 如果events.once() is used to wait for the 'error' event itself, then it is treated as any other kind of event without special handling:events.once()用于等待'error'事件本身，那么它将被视为任何其他类型的事件，而无需特殊处理：
import { EventEmitter, once } from 'node:events';
const ee = new EventEmitter();
once(ee, 'error')
.then(([err]) => console.log('ok', err.message))
.catch((err) => console.error('error', err.message));
ee.emit('error', new Error('boom'));
// Prints: ok boom
An AbortSignal can be used to cancel waiting for the event:AbortSignal可用于取消等待事件：
import { EventEmitter, once } from 'node:events';
const ee = new EventEmitter();
const ac = new AbortController();
async function foo(emitter, event, signal) {
try {
await once(emitter, event, { signal });
console.log('event emitted!');
} catch (error) {
if (error.name === 'AbortError') {
console.error('Waiting for the event was canceled!');
} else {
console.error('There was an error', error.message);
}
}
}
foo(ee, 'foo', ac.signal);
ac.abort(); // Abort waiting for the event
ee.emit('foo'); // Prints: Waiting for the event was canceled!
Optional options: StaticEventEmitterOptionsv11.13.0, v10.16.0
Optional options: StaticEventEmitterOptionsStatic setimport { setMaxListeners, EventEmitter } from 'node:events';
const target = new EventTarget();
const emitter = new EventEmitter();
setMaxListeners(5, target, emitter);
Optional n: numberA non-negative number. The maximum number of listeners per 一个非负数。每个EventTarget event.EventTarget事件的最大侦听器数。
Rest ...eventTargets: (EventEmitter | _DOMEventTarget)[]v15.4.0
Generated using TypeDoc
The MongoClient class is a class that allows for making Connections to MongoDB.MongoClient类是一个允许连接MongoDB的类。Remarks
The programmatically provided options take precedence over the URI options.以编程方式提供的选项优先于URI选项。Example