PromiseRejectionEvent.promise

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 PromiseRejectionEvent事件对象的promise属性是只读的,表明Promise被reject的原因。您可以通过检查PromiseRejectionEvent.reason来了解Promise为什么被reject。

Syntax

promise = PromiseRejectionEvent.promise

Value

一个被reject的,并且错误未被处理的Promise 

Examples

下面的例子监听了未被处理的promise,如果reason 是一个对象,并且其code属性包含了一段文本“Module not read.”,一个空闲的回调函数被声明,当任务执行错误时会进行重试

event.preventDefault() 用来表明该promise已被处理

window.onunhandledrejection = function(event) {
  if (event.reason.code && event.reason.code == "Module not ready") {
    window.requestIdleCallback(function(deadline) {
      loadModule(event.reason.moduleName)
        .then(performStartup);
    });
    event.preventDefault();
  }
}

Specifications

Specification Status Comment
HTML Living Standard
PromiseRejectionEvent.promise
Living Standard Initial definition.

浏览器兼容性

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
promiseChrome Full support 49Edge ? Firefox No support No
Disabled
No support No
Disabled
Disabled This feature is behind the dom.promise_rejection_events.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera No support NoSafari No support NoWebView Android Full support YesChrome Android No support NoEdge Mobile ? Firefox Android No support No
Disabled
No support No
Disabled
Disabled This feature is behind the dom.promise_rejection_events.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Opera Android No support NoSafari iOS No support NoSamsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
User must explicitly enable this feature.
User must explicitly enable this feature.

See also

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