对于您所描述的第一次访问,注册尚未active
当该承诺解决但它是“正在安装”,因此注册的installing
属性将返回一个服务工作者。
由于没有服务人员处于waiting
状态,因此它将转换为activating
,然后转换为active
。所以你是对的,注册财产最初不是active
但刷新,它会。
将下面的代码说明:
navigator.serviceWorker.register('/serviceworker.js').then(onRegistration);
function onRegistration(registration) {
if (registration.waiting) {
console.log('waiting', registration.waiting);
registration.waiting.addEventListener('statechange', onStateChange('waiting'));
}
if (registration.installing) {
console.log('installing', registration.installing);
registration.installing.addEventListener('statechange', onStateChange('installing'));
}
if (registration.active) {
console.log('active', registration.active);
registration.active.addEventListener('statechange', onStateChange('active'));
}
}
function onStateChange(from) {
return function(e) {
console.log('statechange', from, 'to', e.target.state);
}
}
在第一次访问时,console.log
输出将是:
installing ServiceWorker {scriptURL: "http://...", state: "installing", onstatechange: null, onerror: null}
statechange initial state installing changed to installed
statechange initial state installing changed to activating
statechange initial state installing changed to activated
,你观察到的状态的变化同步发生。