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All items in the Front-End Checklist are required for the majority of the projects, but some elements can be omitted or are not essential (in the case of an administration web app, you may not need RSS feed for example). We choose to use 3 levels of flexibility:
means that the item is recommended but can be omitted in some particular situations.
means that the item is highly recommended and can eventually be omitted in some really particular cases. Some elements, if omitted, can have bad repercussions in terms of performance or SEO.
means that the item can't be omitted by any reason. You may cause a dysfunction in your page or have accessibility or SEO issues. The testing priority needs to be on these elements first.
Some resources possess an emoticon to help you understand which type of content / help you may find on the checklist:
📖: documentation or article
🛠: online tool / testing tool
📹: media or video content
Head
Notes: You can find a list of everything that could be found in the <head> of an HTML document.
Meta tag
Doctype: The Doctype is HTML5 and is at the top of all your HTML pages.
<!-- Viewport for responsive web design --><metaname="viewport" content="width=device-width, initial-scale=1">
Title: A title is used on all pages (SEO: Google calculate the pixel width of the characters used in the title, cut off between 472 and 482 pixels. Average character limit would be around 55-characters).
<!-- Document Title --><title>Page Title less than 55 characters</title>
Favicons: Each favicon has been created and displays correctly. If you have only a favicon.ico, put it at the root of your site. Normally you won't need to use any markup. However, it's still good practice to link to it using the example below. Today, PNG format is recommended over .ico format (dimensions: 32x32px).
<!-- Standard favicon --><linkrel="icon" type="image/x-icon" href="https://example.com/favicon.ico"><!-- Recommended favicon format --><linkrel="icon" type="image/png" href="https://example.com/favicon.png">
Apple Touch Icon: Apple touch favicon apple-mobile-web-app-capable are present (Create your Apple Icon file with at least 200x200px dimension to support all dimensions that you may need).
<!-- Apple Touch Icon --><linkrel="apple-touch-icon" href="/custom-icon.png">
RSS feed: If your project is a blog or has articles, an RSS link was provided.
Inline critical CSS: CSS which styles content that is immediately visible during pageload ("above the fold content") is called "critical CSS". It is embedded before your principal CSS call and between <style></style> in a single line (minified).
CSS order: All CSS files are loaded before any JavaScript files in the <head>. (Except the case where sometimes JS files are loaded asynchronously on top of your page).
Social meta
Facebook OG and Twitter Cards are, for any website, highly recommended. The other social media tags can be considered if you target a particular presence on those and want to ensure the display.
Facebook Open Graph: All Facebook Open Graph (OG) are tested and no one is missing or with a false information. Images need to be at least 600 x 315 pixels, 1200 x 630 pixels recommended.
Notes: Using og:image:width and og:image:height will specify the image dimensions to the crawler so that it can render the image immediately without having to asynchronously download and process it.
<metaproperty="og:type" content="website"><metaproperty="og:url" content="https://example.com/page.html"><metaproperty="og:title" content="Content Title"><metaproperty="og:image" content="https://example.com/image.jpg"><metaproperty="og:description" content="Description Here"><metaproperty="og:site_name" content="Site Name"><metaproperty="og:locale" content="en_US"><!-- Next tags are optional but recommended --><metaproperty="og:image:width" content="1200"><metaproperty="og:image:height" content="630">
Error pages: Error 404 page and 5xx exist. Remember that the 5xx error pages need to have their CSS integrated (no external call on the current server).
Noopener: In case you are using external links with target="_blank", your link should have a rel="noopener" attribute to prevent tab nabbing. If you need to support older versions of Firefox, use rel="noopener noreferrer".
Adblockers test: Your website shows your content correctly with adblockers enabled (You can provide a message encouraging people to disable their adblocker).
Webfonts
Notes: Using webfonts may cause Flash Of Unstyled Text/Flash Of Invisible Text - consider having fallback fonts and/or utilizing webfont loaders to control behavior.
Notes: Take a look at CSS guidelines and Sass Guidelines followed by most Front-End developers. If you have a doubt about CSS properties, you can visit CSS Reference. There is also a short Code Guide for consistency.
Responsive Web Design: The website is using responsive web design.
CSS Print: A print stylesheet is provided and is correct on each page.
Preprocessors: Your page is using a CSS preprocessor (Sass is preferred).
Unique ID: If IDs are used, they are unique to a page.
Reset CSS: A CSS reset (reset, normalize or reboot) is used and up to date. (If you are using a CSS Framework like Bootstrap or Foundation, a Normalize is already included into it.)
JS prefix: All classes (or id- used in JavaScript files) begin with js- and are not styled into the CSS files.
<divid="js-slider" class="my-slider"><!-- Or --><divid="id-used-by-cms" class="js-slider my-slider">
Embedded or inline CSS: Avoid at all cost embeding CSS in <style> tags or using inline CSS: only use for valid reasons (e.g. background-image for slider, critical CSS).
Vendor prefixes: CSS vendor prefixes are used and are generated accordingly with your browser support compatibility.
Desktop Browsers: All pages were tested on all current desktop browsers (Safari, Firefox, Chrome, Internet Explorer, EDGE...).
Mobile Browsers: All pages were tested on all current mobile browsers (Native browser, Chrome, Safari...).
OS: All pages were tested on all current OS (Windows, Android, iOS, Mac...).
Pixel perfect: Pages are close to pixel perfect. Depending on the quality of the creatives, you may not be 100% accurate, but your page needs to be close to your template.
Cross Site Request Forgery (CSRF): You ensure that requests made to your server-side are legitimate and originate from your website / app to prevent CSRF attacks.
Content Type Options Prevents Google Chrome and Internet Explorer from trying to mime-sniff the content-type of a response away from the one being declared by the server.
Content Security Policy Defines how content is loaded on your site and from where it is permitted to be loaded. Can also be used to protect against clickjacking attacks.
Lazy loading: Images, scripts and CSS need to be lazy loaded to improve the response time of the current page (See details in their respective sections).
Cookie size: If you are using cookies be sure each cookie doesn't exceed 4096 bytes and your domain name doesn't have more than 20 cookies.
Third party components: Third party iframes or components relying on external JS (like sharing buttons) are replaced by static components when possible, thus limiting calls to external APIs and keeping your users activity private.
Preconnection: DNS lookup, TCP handshake and TLS negotiation with services that will be needed soon is done in advance during idle time using preconnect.
<linkrel="preconnect" href="https://example.com">
Prefetching: Resources that will be needed soon (e.g. lazy loaded images) are requested in advance during idle time using prefetch.
<linkrel="prefetch" href="image.png">
Preloading: Resources needed in the current page (e.g. scripts placed at the end of <body>) in advance using preload.
Structured Data: Pages using structured data are tested and are without errors. Structured data helps crawlers understand the content in the current page.
From https://github.com/thedaviddias/Front-End-Checklist
How to use?
All items in the Front-End Checklist are required for the majority of the projects, but some elements can be omitted or are not essential (in the case of an administration web app, you may not need RSS feed for example). We choose to use 3 levels of flexibility:
Some resources possess an emoticon to help you understand which type of content / help you may find on the checklist:
Head
Meta tag
The next 3 meta tags (Charset, X-UA Compatible and Viewport) need to come first in the head.
favicon.ico
, put it at the root of your site. Normally you won't need to use any markup. However, it's still good practice to link to it using the example below. Today, PNG format is recommended over.ico
format (dimensions: 32x32px).Minimum required xml markup for the browserconfig.xml file is as follows:
rel="canonical"
to avoid duplicate content.HTML tags
lang
attribute of your website is specified and related to the language of the current page.RSS feed: If your project is a blog or has articles, an RSS link was provided.
Inline critical CSS: CSS which styles content that is immediately visible during pageload ("above the fold content") is called "critical CSS". It is embedded before your principal CSS call and between
<style></style>
in a single line (minified).<head>
. (Except the case where sometimes JS files are loaded asynchronously on top of your page).Social meta
Facebook OG and Twitter Cards are, for any website, highly recommended. The other social media tags can be considered if you target a particular presence on those and want to ensure the display.
HTML
Best practices
Error pages: Error 404 page and 5xx exist. Remember that the 5xx error pages need to have their CSS integrated (no external call on the current server).
Noopener: In case you are using external links with
target="_blank"
, your link should have arel="noopener"
attribute to prevent tab nabbing. If you need to support older versions of Firefox, userel="noopener noreferrer"
.HTML testing
Webfonts
Webfont size: Webfont sizes don't exceed 2 MB (all variants included).
Webfont loader: Control loading behavior with a webfont loader
CSS
<style>
tags or using inline CSS: only use for valid reasons (e.g. background-image for slider, critical CSS).Performance
CSS testing
Responsive web design: All pages were tested at the following breakpoints: 320px, 768px, 1024px (can be more / different according to your analytics).
CSS Validator: The CSS was tested and pertinent errors were corrected.
Images
Best practices
width
andheight
attributes on<img>
if the final rendered image size is known (can be omitted for CSS sizing).<img>
have an alternative text which describe the image visually.JavaScript
Best practices
.min
suffix).async
or deferred usingdefer
attribute.<html>
tag.JavaScript testing
Security
Scan and check your web site
Best practices
Performance
Best practices
Minified HTML: Your HTML is minified.
Lazy loading: Images, scripts and CSS need to be lazy loaded to improve the response time of the current page (See details in their respective sections).
Cookie size: If you are using cookies be sure each cookie doesn't exceed 4096 bytes and your domain name doesn't have more than 20 cookies.
Preparing upcoming requests
dns-prefetch
.preconnect
.prefetch
.<body>
) in advance usingpreload
.Performance testing
Accessibility
Best practices
Headings
Landmarks
<header>
hasrole="banner"
.<nav>
hasrole="navigation"
.<main>
hasrole="main"
.Semantics
Form
aria-label
instead.Accessibility testing
SEO
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