Ctrl + f5 là gì
I once did experiment in IE6 và Firefox 2.x. The F5 refresh would trigger a HTTP request sent khổng lồ the vps with an If-Modified-Since header, while Ctrl + F5 would not have such a header. In my understanding, F5 will try khổng lồ utilize cached nội dung as much as possible, while Ctrl + F5 is intended to lớn abandon all cached nội dung and just retrieve all content from the servers again.
But today, I noticed that in some of the latest browsers (Chrome, IE8) it doesn”t work in this way anymore. Both F5 and Ctrl + F5 send the If-Modified-Since header.
So how is this supposed to lớn work, or (if there is no standard) how vị the major browsers differ in how they implement these refresh features?
http browser caching cross-browser refresh giới thiệu Improve this question Follow edited Apr 9 “16 at 9:51
Krzysztof Krasoń 23k1414 gold badges7777 silver badges9999 bronze badges asked Dec 22 “08 at 2:00
Morgan ChengMorgan Cheng 65.6k6363 gold badges165165 silver badges223223 bronze badges 3 add a comment |
6 Answers 6
Active Oldest Votes326Generally speaking:
F5 may give you the same page even if the nội dung is changed, because it may load the page from cache. But Ctrl-F5 forces a cache refresh, & will guarantee that if the nội dung is changed, you will get the new content.Bạn vẫn xem: Ctrl f5 là gì
share Improve this answer Follow edited Mar 11 “14 at 9:20
naXa 25.8k1414 gold badges153153 silver badges212212 bronze badges answered Dec 22 “08 at 2:10
dancavallarodancavallaro 12.5k77 gold badges3333 silver badges3333 bronze badges 4 showroom a bình luận | 526It is up khổng lồ the browser but they behave in similar ways.
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I have tested FF, IE7, Opera and Chrome.
F5 usually updates the page only if it is modified. The browser usually tries to lớn use all types of cache as much as possible và adds an “If-modified-since” header to the request. Opera differs by sending a “Cache-Control: no-cache”.
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CTRL-F5 is used to lớn force an update, disregarding any cache. IE7 adds an “Cache-Control: no-cache”, as does FF, which also adds “Pragma: no-cache”. Chrome does a normal “If-modified-since” and Opera ignores the key.
Edit: Updated table
The table below is updated with information on what will happen when the browser”s refresh-button is clicked (after a request by Joel Coehoorn), & the “max-age=0” Cache-control-header.
Updated table, 27 September 2010
┌────────────┬───────────────────────────────────────────────┐│ UPDATED │ Firefox 3.x ││27 SEP 2010 │ ┌────────────────────────────────────────────┤│ │ │ MSIE 8, 7 ││ Version 3 │ │ ┌─────────────────────────────────────────┤│ │ │ │ Chrome 6.0 ││ │ │ │ ┌──────────────────────────────────────┤│ │ │ │ │ Chrome 1.0 ││ │ │ │ │ ┌───────────────────────────────────┤│ │ │ │ │ │ Opera 10, 9 ││ │ │ │ │ │ ┌────────────────────────────────┤│ │ │ │ │ │ │ │├────────────┼──┼──┼──┼──┼──┼────────────────────────────────┤│ F5│IM│I │IM│IM│C │ ││ SHIFT-F5│- │- │CP│IM│- │ Legend: ││ CTRL-F5│CP│C │CP│IM│- │ I = “If-Modified-Since” ││ ALT-F5│- │- │- │- │*2│ p = “Pragma: No-cache” ││ ALTGR-F5│- │I │- │- │- │ C = “Cache-Control: no-cache” │├────────────┼──┼──┼──┼──┼──┤ M = “Cache-Control: max-age=0” ││ CTRL-R│IM│I │IM│IM│C │ – = ignored ││CTRL-SHIFT-R│CP│- │CP│- │- │ │├────────────┼──┼──┼──┼──┼──┤ ││ Click│IM│I │IM│IM│C │ With “click” I refer lớn a ││ Shift-Click│CP│I │CP│IM│C │ mouse click on the browsers ││ Ctrl-Click│*1│C │CP│IM│C │ refresh-icon. ││ Alt-Click│IM│I │IM│IM│C │ ││ AltGr-Click│IM│I │- │IM│- │ │└────────────┴──┴──┴──┴──┴──┴────────────────────────────────┘Versions tested:
Firefox 3.1.6 and 3.0.6 (WINXP)MSIE 8.0.6001 và 7.0.5730.11 (WINXP)Chrome 6.0.472.63 và 1.0.151.48 (WINXP)Opera 10.62 & 9.61 (WINXP)
Notes:
Version 3.0.6 sends I và C, but 3.1.6 opens the page in a new tab, making a normal request with only “I”.
Note about Chrome 6.0.472: If you vì a forced reload (like CTRL-F5) it behaves like the url is internally marked lớn always vì a forced reload. The flag is cleared if you go to the address bar and press enter.
