--- title: Client.postMessage() slug: Web/API/Client/postMessage translation_of: Web/API/Client/postMessage ---

{{SeeCompatTable}}{{APIRef("Client")}}

{{domxref("Client")}} 接口的 Client.postMessage() 方法允许一个service worker客户端向一个  {{domxref("ServiceWorker")}}发送一个消息，会触发service worker的message事件，通过监听这个事件，可以获取这个消息。

语法

Client.postMessage(message[, transfer]);

返回

Void.

参数

message
发送给service worker的消息内容。
transfer {{optional_inline}}
可转移的对象，例如对端口的引用。

例子

从 service worker 向 client 发送消息：

addEventListener('fetch', event => {
  event.waitUntil(async function() {
    // Exit early if we don't have access to the client.
    // Eg, if it's cross-origin.
    if (!event.clientId) return;

    // Get the client.
    const client = await clients.get(event.clientId);
    // Exit early if we don't get the client.
    // Eg, if it closed.
    if (!client) return;

    // Send a message to the client.
    client.postMessage({
      msg: "Hey I just got a fetch from you!",
      url: event.request.url
    });

  }());
});

接收message:

navigator.serviceWorker.addEventListener('message', event => {
  console.log(event.data.msg, event.data.url);
});

Specifications

Specification Status Comment
{{SpecName('Service Workers', '#client-postmessage-method', 'postMessage()')}} {{Spec2('Service Workers')}} Initial definition.

Browser compatibility

{{Compat("api.Client.postMessage")}}