[英]Using 'defer' attribute with scripts before the body tag
我在Google網頁測試工具上運行了我的網頁，並建議我使用'defer'或'async'屬性來消除渲染阻止JS。 我的HTML是這樣的：
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>My Page</title>
<link href="https://mycdn.com/style.css" rel="stylesheet">
</head>
<body>
<div id="app-container"></div>
<script type="text/javascript" src="https://mycdn.com/shared.js"></script>
<script type="text/javascript" src="https://mycdn.com/main.js"></script>
</body>
</html>
因為，我的腳本在'body'標簽關閉之前就包含了，而不是在'head'中，它們真的阻塞了嗎？ 在解析結束的“ html”之前，不會進行繪制嗎？
使用異步或延遲或將腳本移動到文件底部並不總是在不同的瀏覽器上都有效，一種建議的外部腳本加載方式是通過以下方式加載該腳本：將這段代碼放在身體標簽。
<script type="text/javascript">
function downloadJSAtOnload(){
var element = document.createElement("script");
element.src = "defer.js"; // Replace "defer.js" with your url or filename
document.body.appendChild(element);
}
if (window.addEventListener) window.addEventListener("load", downloadJSAtOnload, false);
else if(window.attachEvent) window.attachEvent("onload", downloadJSAtOnload);
else window.onload = downloadJSAtOnload;
</script>
defer 應該在剛好在正文結束標記之前加載的腳本中使用嗎？
[英]Should defer be used in scripts that are loaded just before the body closing tag?
使用“延遲”屬性時是否需要將腳本放在頁面底部？
[英]Is it necessary to put scripts at the bottom of a page when using the "defer" attribute?
是不是寫的比較快<script defer> just before the </ head> tag than before the </ body> tag until the processing is completed?
[英]Is it faster to write <script defer> just before the </ head> tag than before the </ body> tag until the processing is completed?
我應該在已經位於底部正文標記之前的腳本上使用 defer 嗎？
[英]Should I use defer on script which are already at just before the bottom body tag?
Javascript非阻塞腳本，為什么不簡單地放入所有腳本 </body> 標簽？
[英]Javascript non-blocking scripts, why don't simply put all scripts before </body> tag?
在結束正文標記的末尾添加延遲到腳本標記是多余的嗎？
[英]Is adding defer to a script tag at the end of a closing body tag redundant?
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