Created
May 1, 2018 08:03
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check html version with meta content / 以 meta 檢查 html 版本
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// 可搭配 pug 產生 version meta | |
// 例:<meta name="version" content="1589465168"> // content 可用 Date.now() 產生 | |
if (!Date.now) { | |
Date.now = function now() { | |
return new Date().getTime(); | |
}; | |
} | |
function checkVersionMatch() { | |
if (window.XMLHttpRequest) { // Mozilla, Safari, IE7+ ... | |
var httpRequest = new XMLHttpRequest(); | |
httpRequest.onreadystatechange = function(){ | |
if (httpRequest.readyState === XMLHttpRequest.DONE) { | |
if (httpRequest.status === 200) { | |
// alert(httpRequest.responseText); | |
var parser = new DOMParser(); | |
var doc = parser.parseFromString(httpRequest.responseText, "text/html"); | |
// console.log(doc); | |
// console.log(getVersion(doc)); | |
// console.log(getVersion(document)); | |
if (getVersion(document) === "") { | |
// no meta | |
} else { | |
if (getVersion(document) !== getVersion(doc)) { | |
// version no match, reload html with some cache buster | |
location.search = location.search + "&_=" + Date.now(); | |
} else { | |
// version match | |
} | |
} | |
} else { | |
// alert('There was a problem with the request.'); | |
} | |
} | |
}; | |
httpRequest.open('GET', location.origin + location.pathname + '?' + Date.now(), false); | |
httpRequest.send(); | |
} | |
} | |
function getVersion(doc) { | |
var metas = doc.getElementsByTagName("meta"); | |
for (var i = 0; i < metas.length; i++) { | |
var attrs = metas[i].attributes; | |
for (var j = 0; j < attrs.length; j++) { | |
if (attrs[j].name && attrs[j].name === "version") { | |
return attrs[j].content; | |
} | |
} | |
} | |
return ""; | |
} |
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