ServiceWorker.onstatechange

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2018.

实验性: 这是一项实验性技术
在将其用于生产之前,请仔细检查浏览器兼容性表格

一个 EventListener 联动的属性,其会被任何 stagechange 类型事件抛出时联动; 它也基本上能在任何时候ServiceWorker.state 改变时被抛出。

语法

ServiceWorker.onstatechange = function(statechangeevent) { ... }
ServiceWorker.addEventListener('statechange', function(statechangeevent) { ... } )

示例

这段代码出自 service worker registration-events sample (live demo). 它会监听 ServiceWorker.state 的改变并返回它的值。

js
var serviceWorker;
if (registration.installing) {
  serviceWorker = registration.installing;
  document.querySelector("#kind").textContent = "installing";
} else if (registration.waiting) {
  serviceWorker = registration.waiting;
  document.querySelector("#kind").textContent = "waiting";
} else if (registration.active) {
  serviceWorker = registration.active;
  document.querySelector("#kind").textContent = "active";
}

if (serviceWorker) {
  logState(serviceWorker.state);
  serviceWorker.addEventListener("statechange", function (e) {
    logState(e.target.state);
  });
}

注意当statechange 抛出时,service worker 的引用可能已经改变。例如:

js
navigator.serviceWorker.register(..).then(function(swr) {
  swr.installing.state == "installing"
  swr.installing.onstatechange = function() {
    swr.installing == null;
    // At this point, swr.waiting OR swr.active might be true. This is because the statechange
    // event gets queued, meanwhile the underlying worker may have gone into the waiting
    // state and will be immediately activated if possible.
  }
})

规范

Specification
Service Workers
# dom-serviceworker-onstatechange

浏览器兼容性

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
statechange event

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support