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Use of H5 cache Manifest

php中世界最好的语言Original: 2018-03-16 11:25:442729browse

This time I will bring you the use of H5 cache Manifest. What are the precautions for using H5 cache Manifest? The following is a practical case, let's take a look. In the app

Update

h5 page has always had a cache problem. By default, by doing nothing, the app has a certain amount of space to cache pages. The update will be loaded immediately after it is started. When the app cache space is available, the update will not be downloaded. Android can clear cache space, but iOS can only uninstall and reinstall (are u kidding me?). This is the worst case scenario, you can change the address. no-cache

After noticing this, add no-cache.

<meta http-equiv="Cache-Control" content="no-cache">

to tell the browser not to cache the page. In fact, when the page has not changed, the request is 304, and if the page has changed, it is 200. So adding no-cache does not mean that it will be downloaded completely every time, but that it will be downloaded again when it is updated. But at this time, different mobile phones still perform differently. 4s and 6sp are different. Visit the same page and modify the js. The 4s has been updated, but the 6sp is still the same. How to fix it, because there is still cache on the server side. First set the nginx cache:

 location / {
           root   html;           expires -1;
           index  index.html index.htm;
        }

and need to restart nginx:

nginx -s reload

At this time, 6sp has also been updated.

But always restarting nginx is not a solution, it may cause some requests to be lost. And in this case, it is completely unusable offline. For example, when the Internet is disconnected and I try to send a message, the originally set picture with a red exclamation mark and the character's avatar cannot be displayed. Of course, you can convert it into a base64

string

to solve this problem. Base64 is very long and takes up space wherever it is placed. How to solve it, manifest

no-cache+update file name+update address to be tested

manifest

For introduction, you can read w3shool first: http:/ /www.w3school.com.cn/html5/html_5_app_cache.asp , here is the usage.

1.Set html

<html manifest="index.appcache">

2.Set cache directory

CACHE MANIFEST
#v1.0.0.0#需要缓存的文件js/zepto.js#不需要缓存的页面
NETWORK:*#无法访问页面
FALLBACK404.html

3.Set nginx mime

text/cache-manifest         appcache;

mime types files are all in the conf directory. After starting nginx. At this time, the page will load:

This picture illustrates two things. One is that the process will first download index.appcache, and then the checking event and download event will be triggered one after another. , progress event and updateReady event. Two of them cache the current page by default. And it actually takes a parameter and caches it. It seems that as long as the current pages with different addresses are cached (I only wrote one zepto in the cache directory above). Refresh the page again:

If index.appcache is not updated, the check will not be triggered.

Loading cached files

Status

is 200, and the size column is from cache. The one loaded from the browser is 304, one is a few milliseconds, and the other is more than ten milliseconds. F12 enters developer mode, and you can see the cached files in the Application cache column.

#But it cannot be cleaned in this place. It needs to be cleaned by clear storage in Application.

Update cached files

The most obvious one is the homepage, which is cached by default. At this time, it will have no effect if you change the content of the homepage without modifying index.appache. For example, if you delete the

reference

of a js, the client still downloads the js. At this time, you need to modify this cache file:

#不需要缓存的页面
NETWORK:  
mobile/index.html
*

Notice that although index.appache and index are at the same level, index.html cannot be written, and the path equivalent to the website must be written. The same is true for other resources. At this time, the update is triggered, but the page is still loaded with cached resources, so another process needs to be done:

  window.applicationCache.addEventListener("updateready", function(){
    location.reload()
  });

这样才会加载最新的页面。如果首页再发生修改，可以随意(加个空格，加空行)修改缓存文件，就能触发更新。所以剩下的问题就是记得在更新资源之后记得更新缓存文件。建议就是不变的资源(框架样式，框架js，图片)缓存下来，经常要修改的js就让浏览器缓存吧。现在这样就避免了reload nginx。这个效果要比加no-cache的方法好。当然，如果无所谓消息或者reload的影响。no-cache还是很方便，毕竟这个index.appache一旦加上，难以去掉，除非清理缓存。

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