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App Loader with Update Manager
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<body><script> | |
/* SET `$appurl` as argument to the IIFE | |
to load any javascript (localstorage size limit 5mb) | |
The first page visit will load the whole script, follow-up visits | |
load the cached script right away and if a new version is available, | |
offer to update the app now or later. | |
(The caching only works if the server sends `header.etag`) | |
I welcome suggestions/questions/discussions - just drop me a message :-) | |
http://twitter.com/serapath | |
*/ | |
;(function($appurl){ | |
var $appkey = 'app("'+$appurl+'").app' | |
var $etagkey = 'app("'+$appurl+'").etag' | |
var $app = localStorage.getItem($appkey)||'' | |
var fresh = $app === '' ? true : false, | |
var $etag = localStorage.getItem($etagkey) | |
log() | |
try { | |
$app && start($app) | |
updateManager('HEAD') | |
} catch (e) { | |
localStorage.removeItem($appkey) | |
localStorage.removeItem($etagkey) | |
start(undefined, $appurl) | |
} | |
function start (script, url, s) { | |
document.body.innerHTML = '' | |
s=document.createElement('script') | |
if (url) s.setAttribute('src',url) | |
else s.innerHTML=script | |
document.body.appendChild(s) | |
} | |
function updateManager (m, xhr, hJSON, h, tmp) { | |
xhr=new XMLHttpRequest() | |
xhr.open(m,$appurl) | |
xhr.onload=function(response){ | |
hJSON={} | |
h=xhr.getAllResponseHeaders() | |
h.match(/([^\n\r:]+):([^\n\r]+)/g).forEach(function(item){ | |
tmp=item.split(': ') | |
hJSON[tmp[0]]=tmp[1] | |
}) | |
m === 'GET' ? ( | |
$etag = hJSON.etag, | |
$app = this.response, | |
log(), | |
localStorage.setItem($appkey, $app), | |
localStorage.setItem($etagkey, $etag), | |
// @TODO: write better update manager | |
(fresh ? location.href=location.href : 0) | |
) : hJSON['etag'] !== $etag ? updateManager('GET') : 0 | |
} | |
xhr.send() | |
} | |
function log () { | |
console.log( | |
'\n\n\nTotal Application Size: ~'+parseInt($app.length/1024)+ | |
'kb <Version='+$etag+'>\n\n\n' | |
) | |
} | |
})('SOURCE/public/bundle.js') | |
</script></body> |
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