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This article mainly explains "what is the meaning of each field of window performance". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "what is the meaning of each field of window performance"?

The complete structure of the window.performance object

The memory field represents the memory footprint of JavaScript.

The navigation field counts some data related to web navigation:

RedirectCount: number of redirects (read-only), but this interface is restricted by homologous policy, that is, only homologous redirects can be detected.

The return value of type should be one of 0meme 1 and 2. Each corresponds to three enumerated values:

0:TYPE_NAVIGATE (users visit the page through regular navigation, such as clicking a link, or the general get method)

1:TYPE_RELOAD (users access the page by refreshing, including JS calling refresh API, etc.)

2:TYPE_BACK_FORWARD (users access this page through the back button)

The most important thing is the statistics of the timing field, which contains a series of time data such as network, parsing and so on.

The meaning of each field of window.performance

StartTime: some browsers are implemented as navigationStart, which represents the start time node of the previous page document before the browser starts unload. For example, we are currently browsing baidu.com, enter google.com in the address bar and enter, and the action executed by the browser is as follows: unload the current document (i.e. baidu.com)-> request the next document (i.e. google.com). The value of navigationStart is the time node that triggers the unload's current document.

If the current document is empty, the value of navigationStart is equal to fetchStart.

RedirectStart and redirectEnd: if the page is from redirect, redirectStart and redirectEnd represent the time nodes where the redirect starts and ends, respectively

UnloadEventStart and unloadEventEnd: if the previous document and the requested document are in the same domain, unloadEventStart and unloadEventEnd represent the start and end time nodes of the previous document in the browser unload, respectively. Otherwise, both are equal to 0.

FetchStart is the value of time before the browser initiates any request. Between fetchStart and domainLookupStart, the browser checks the cache of the current document

DomainLookupStart and domainLookupEnd represent the start and end time nodes of the DNS query, respectively. If the browser does not make a DNS query (such as using cache), then both values are equal to fetchStart

ConnectStart and connectEnd represent the time nodes for TCP to establish a connection and successfully connect, respectively. If the browser does not make a TCP connection (such as using a persistent connection to webscoket), both are equal to domainLookupEnd.

At this point, I believe you have a deeper understanding of "what is the meaning of each field of window performance". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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