标签：var lines ensure ice font syn style and ddl
The HTML code is minified, comments, white spaces and new lines are removed from production files. 
Ensure that comments are removed from your pages. Type attributes like type="text/javascript" or type="text/css" are not required anymore and should be removed.
Ensure that your CSS is always loaded before having JavaScript code. Use iframes only if you don‘t have any other technical possibility. Try to avoid as much as you can iframes. All CSS files are minified, comments, white spaces and new lines are removed from production files. CSS files are concatenated in a single file (Not always valid for HTTP/2).（合并css，减少http请求，http2不必） CSS files need to be non-blocking to prevent the DOM from taking time to load.（css必须是非阻塞的）rel attribute with the preload value and add as="style" on the <link> element<link rel="preload" href="a.css" as="style" onload="this.rel=‘stylesheet‘"> <noscript><link rel="stylesheet" href="a.css"></noscript>
The length of your classes can have an (slight) impact on your HTML and CSS files (eventually). Remove unused CSS selectors. The CSS critical (or "above the fold") collects all the CSS used to render the visible portion of the page. It is embedded before your principal CSS call and between <style></style> in a single line (minified if possible). Avoid using embed or inline CSS inside your <body> (Not valid for HTTP/2) Analyzing your stylesheets can help you to flag issues, redundancies and duplicate CSS selectors. You are using WOFF2 on your web project or application.preconnect to load your fonts faster: <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
Webfont sizes don‘t exceed 300kb (all variants included) Avoid transparent text until the Webfont is loaded Your images are optimized, compressed without direct impact to the end user. Choose your image format appropriately. Prefer using vector image rather than bitmap images (when possible). Set width and height attributes on <img> if the final rendered image size is known. You could eventually convert tiny images to base64 but it‘s actually not the best practice. Images are lazyloaded (A noscript fallback is always provided). Ensure to serve images that are close to your display size.（srcset和picture了解一下） All JavaScript files are minified, comments, white spaces and new lines are removed from production files (still valid if using HTTP/2). (Only valid for website) Avoid having multiple JavaScript codes embedded in the middle of your body. Regroup your JavaScript code inside external files or eventually in the <head> or at the end of your page (before </body>). JavaScript files are loaded asynchronously using async or deferred using defer attribute. All JavaScript libraries used in your project are necessary (prefer Vanilla JavaScript for simple functionalities), updated to their latest version and don‘t overwhelm your JavaScript with unnecessary methods. Ensure to use wisely external libraries, most of the time, you can use a lighter library for a same functionality.（比如dayjs替代了momentjs） Check for performance problems in your JavaScript files (and CSS too). Reduce the size of your page + resources as much as you can. Reduce as much as possible your page load times to quickly deliver your content to your users. Reduce as much as you can the time your browser waits before receiving data. If you are using cookies be sure each cookie doesn‘t exceed 4096 bytes（4kb） and your domain name doesn‘t have more than 20 cookies. Always ensure that every file requested are essential for your website or application. Use a CDN to deliver faster your content over the world. Avoid having your website using HTTPS and serve files coming from source using HTTP. Avoid requesting unreachable files (404). Set HTTP headers to avoid expensive number of roundtrips between your browser and the server.标签：var lines ensure ice font syn style and ddl
原文地址：https://www.cnblogs.com/colima/p/9389086.html
