html - 更改或设置 src 或 srcDoc 属性时是否丢弃了 iframe 的 Web 浏览上下文？

Question

根据 HTML5 官方规范，他们声明:

When an iframe element is removed from a document, the user agent must discard the nested browsing context, if any

所以我想知道如果我更改 src 或 srcDoc 属性，浏览上下文是否也会被丢弃。

规范也提到了它:

When the user agent is to process the iframe attributes, it must run the first appropriate steps from the following list

但我不清楚设置/更改此属性是否会丢弃当前浏览上下文。如果不是，JavaScript 执行上下文是否会被丢弃？

Answer 1

如果设置的 URL 与前一个 URL 的片段不同，那么简短的回答是肯定的。

又长又复杂answer is given in the current specification (顺便说一句，is now the "HTML living standard" of the WHATWG):

Whenever an iframe element with a non-null nested browsing context hasits srcdoc attribute set, changed, or removed, the user agent mustprocess the iframe attributes.

Similarly, whenever an iframe element with a non-null nested browsingcontext but with no srcdoc attribute specified has its src attributeset, changed, or removed, the user agent must process the iframeattributes.

steps for processing the iframe attributes状态:

If element's srcdoc attribute is specified, then:…Navigate to the srcdoc resource: navigate an iframe or frame given element…if element has a src attribute specified, or initialInsertion is false, then run the shared attribute processing steps for iframe and frame elements given element.

steps to navigate an iframe or frame这么说:

Navigate element's nested browsing context to resource…

最后，navigating a browsing context定义这个:

If historyHandling is not "reload", resource is a request, resource'surl equals browsingContext's active document's URL with excludefragments flag set, and resource's url's fragment is non-null, then:

Navigate to a fragment given browsingContext

…Otherwise, resource is a request whose url's scheme is neither "javascript" nora fetch scheme

Run process a navigate URL scheme given resource's url and browsingContext.

此时浏览上下文更改为新资源。

请注意，规范中引用的部分仅反射(reflect)片段和将 URL 更改为“javascript”或获取方案 URL 以外的其他内容的情况。