Pattern

What is it

When to use it

How to use it

The tabbed user interface enables users to jump to their target section quickly. Tabs present like logically group information on the same page. Information should

be logically chunked and ordered
be arallel in nature
show user's context
obvious where they begin and end

Users should not need to see content of multiple tabs simultaneously and the user should be able to easily recognise where they are within the content.

The tab module can be initialised by importing a file with the javascript module using import * as tabs from "../pg/patterns/layouts/tabs/_tabs.js"; contains a modularized version of the jQuery code, so that it can be called on demand. It is what is used in the design system so that the JavaScript can be called at run time (after loading content).

div#uniqueID.tab-group
	div(data-tab="[tab title]")
	div(data-tab="[tab title]")

tabset, .tab-group {
	margin: 2rem 0 1rem 0;
}
tabset > ul, .tab-group > ul {
	display: -webkit-box;
	display: -ms-flexbox;
	display: flex;
	margin: 0;
	padding: 0;
}
tabset > ul li.separator, .tab-group > ul li.separator {
	border-bottom: 1px solid var(--colour-grey);
	border-left: 1px solid var(--colour-grey);
	display: inline-block;
	margin: 0.45rem 0 0 0;
	width: 100%;
}
tabset .tab-hidden, .tab-group .tab-hidden {
	display: none;
}
tabset [role=tab], .tab-group [role=tab] {
	background-color: var(--colour-white);
	border-left: 1px solid var(--colour-grey);
	border-top: 1px solid var(--colour-grey);
	border-radius: 0.5rem 0.5rem 0 0;
	cursor: pointer;
	margin: 0;
	display: inline;
	padding: 1rem 1.5rem 0.14rem 1.5rem;
	z-index: 2;
}
tabset [role=tab]:last-of-type, .tab-group [role=tab]:last-of-type {
	border-right: 1px solid var(--colour-grey);
}
tabset [role=tab]:not(.selected), .tab-group [role=tab]:not(.selected) {
	background-color: var(--colour-grey-xxl);
	border-bottom: 1px solid var(--colour-grey);
}
tabset [role=tab] span, .tab-group [role=tab] span {
	display: block;
	margin: 0 0 0.5rem 0;
}
tabset [role=tabpanel], .tab-group [role=tabpanel] {
	background-color: var(--colour-white);
	border: 1px solid var(--colour-grey);
	border-top: none;
	padding: 1rem;
	z-index: 1;
}
tabset [role=tabpanel]:not(.open), .tab-group [role=tabpanel]:not(.open) {
	display: none;
}

//		DS2 core (c) 2024 Alexander McIlwraith 
//		Licensed under CC BY-SA 4.0 

$tab-border: #7f7f7f !default; 
$tab-selected: #FFF !default;
$tab-notselected: #f0f0f0 !default;

@mixin tabs {
	tabset, .tab-group {
		margin: 2rem 0 1rem 0;
		> ul {
			display: flex;
			margin: 0;
			padding: 0;

			li.separator {	
				border-bottom: 1px solid $tab-border;
				border-left: 1px solid $tab-border;
				display: inline-block;
				margin: .45rem 0 0 0;
				width: 100%;
			}
		}

		.tab-hidden {
			display: none;
		}

		[role="tab"] {
			background-color: $tab-selected;
			border-left: 1px solid $tab-border;
			border-top: 1px solid $tab-border;
			border-radius: .5rem .5rem 0 0;
			cursor:pointer;
			margin: 0;
			display: inline;
			padding: 1rem 1.5rem .14rem 1.5rem;
			z-index: 2;
			
			&:last-of-type {
				border-right: 1px solid $tab-border;
			}

			&:not(.selected) {
				background-color: $tab-notselected;
				border-bottom: 1px solid $tab-border;
			}

			span {
				display: block;
				margin: 0 0 .5rem 0;
			}

		}
		[role="tabpanel"] {
			background-color: $tab-selected;
			border: 1px solid $tab-border;
			border-top: none;
			padding: 1rem;
			z-index: 1;

			&:not(.open) {
				display: none;
			}
			@content;

		}
	}
}

/*  DS2 core (c) 2024 Alexander McIlwraith 
	import * as tabs from "../pg/patterns/layouts/tabs/_tabs.js";
	tabs.init();
 */

export function init(p = document) { 
	p.querySelectorAll(".tab-group, tabset").forEach(tabGroup => {

		if (tabGroup.querySelector("[role=tablist]") === null) {
			const tabgroup = tabGroup.getAttribute("id");
			let tablist = "";

			Array.from(tabGroup.children).forEach(child => {
				const tab = child.getAttribute("tab") || child.getAttribute("data-tab");
				if (tab !== null) {
					const tabID = tab.replace(/\W+/g, "-").toLowerCase();
					const tabPanel = document.createElement('div');
					tabPanel.id = `tab-panel-${tabgroup}-${tabID}`;
					tabPanel.className = tablist === "" ? "open" : "";
					tabPanel.setAttribute("role", "tabpanel");
					tabPanel.setAttribute("tabindex", "0");
					tabPanel.setAttribute("aria-labelledby", `tab-${tabgroup}-${tabID}`);
					tabPanel.appendChild(child.cloneNode(true));
					child.parentNode.replaceChild(tabPanel, child);
					tablist += `${tab}`;
				} else {
					child.classList.add("tab-hidden");
				}
			});

			const ul = document.createElement('ul');
			ul.setAttribute("role", "tablist");
			ul.innerHTML = `${tablist}`;
			tabGroup.insertBefore(ul, tabGroup.firstChild);

			tabGroup.querySelectorAll('[role="tab"]').forEach(tab => {
				tab.addEventListener("click", () => {
					const siblings = Array.from(tab.parentNode.children);
					siblings.forEach(sibling => sibling.classList.remove("selected"));
					tab.classList.add("selected");

					const tabPanels = Array.from(tab.parentNode.parentNode.children)
										   .filter(child => child.getAttribute("role") === "tabpanel");
					tabPanels.forEach(panel => panel.classList.remove("open"));

					const tabPanelId = tab.getAttribute("id").replace("tab", "tab-panel");
					document.getElementById(tabPanelId).classList.add("open");
				});
			});
			
		}
	});
}