File Tabs

Abstract
The rwt-file-tabs web component is a thin bar containing named file tabs. It is typically used with apps that allow multiple files to be worked on simultaneously.

Motivation

The rwt-file-tabs web component can be used in scenarios with multiple views or multiple work tasks.

This component can be configured with a fixed set of tabs which are slotted into the component when designing the document. Alternatively, its programming API allows tabs to be created and removed as needed, when working with a dynamic set of tabs.

Tabs can be configured using CSS to adjust their size and typography.

The tab bar occupies a fixed width. When the size of all tabs exceeds that width, scroll buttons are automatically enabled.

Dynamic tabs can be closable or not, based on an attribute set on the web component by the developer.

Prerequisites

The rwt-file-tabs web component works in any browser that supports modern W3C standards. Templates are written using BLUEPHRASE notation, which can be compiled into HTML using the free Read Write View desktop app. It has no other prerequisites. Distribution and installation are done with either NPM or via Github.

Installation using NPM

If you are familiar with Node.js and the package.json file, you'll be comfortable installing the component just using this command:

npm install rwt-file-tabs
						

If you are a front-end Web developer with no prior experience with NPM, follow these general steps:

• Install Node.js/NPM on your development computer.
• Create a package.json file in the root of your web project using the command:

npm init
							

• Download and install the web component using the command:

npm install rwt-file-tabs
							

Important note: This web component uses Node.js and NPM and package.json as a convenient distribution and installation mechanism. The web component itself does not need them.

Installation using Github

If you are more comfortable using Github for installation, follow these steps:

• Create a directory node_modules in the root of your web project.
• Clone the rwt-file-tabs web component into it using the command:

git clone https://github.com/readwritetools/rwt-file-tabs.git
							

Using the web component

After installation, you need to add a few things to your HTML page to make use of it.

• Add a script tag to load the component's rwt-file-tabs.js file:

<script src='/node_modules/rwt-file-tabs/rwt-file-tabs.js' type=module></script>
							

• Add the component tag somewhere on the page, configuring it with these optional attributes:
• closable This optional attribute instructs the component to add an 'x' button to each dynamically added tab, allowing the user to remove the tab.
• scroll-side={left|right} When the space occupied by the tabs is too large, scroll buttons are enabled. They can be positioned to the left or the right of the tabs.
• anchor-side={left|right} When the space occupied by the tabs is less than the width of the component, the unoccupied space can be anchored to the left or to the right of the tabs.
• role=navigation This web accessible ARIA attribute tells readers that the component is used for navigation.

Slotted usage

If the component is to be used with a predetermined set of tabs, they can be slotted in. Here's an example:

<rwt-file-tabs role=contentinfo>
    <button slot=tabitem id=tab1 title='Read only view'>READ</button>
    <button slot=tabitem id=tab2 title='Text editing view'>WRITE</button>
    <button slot=tabitem id=tab3 title='Web browser preview'>PREVIEW</button>
</rwt-file-tabs>
						

Programmatic API

If the component is to be used with a dynamic set of tabs, they can be added and removed using these methods.

insertTab(id, value, title)

The id should be a unique identifier. It will be used for manipulating the tab.

The value is the text to display on the tab. Text that is too long will be ellipsed.

The title parameter is optional, and if provided will be used as the hover tooltip.

removeTab(id)

The id is the identifier of the tab to remove.

getCurrentTab()

Returns an object with two values: currentTabId and currentTabValue.

setCurrentTab(id)

Changes the current tab to be the one identified with id.

getScrollableOverflow()

The size, in pixels, of the tabs that are hidden when the component isn't wide enough for all of them.

setScrollPosition(left)

The left parameter is the number of pixels to programmatically scroll the tabs. It should be an integer from 0 to scrollableOverflow.

scrollMaxRight()

Scroll the tabs all the way to the right. This is only meaningful when there is scrollable overflow.

Life-cycle events

The component issues life-cycle events.

component-loaded

Sent when the component is fully loaded and ready to be used. As a convenience you can use the waitOnLoading() method which returns a promise that resolves when the component-loaded event is received. Call this asynchronously with await.

tab-activated

Sent when the user switches to a new tab. The event argument has a detail property containing the currentTabId and currentTabValue of the newly activated tab.

tab-closing

Sent when the user clicks on the 'x' to close a tab. This event allows the developer to determine if it's safe to close the tab. Use preventDefault() to cancel the operation. The event argument has a detail property containing the currentTabId and currentTabValue of the item about to be closed.

Styling

Tab styling

The component can be styled with these CSS variables:

rwt-file-tabs {
    --width: 100%;
    --height: 2rem;
    --nav-button-size: 1.6rem;
}
						

The tabs can be styled with these CSS variables:

rwt-file-tabs {
    --font-weight: normal;
    --letter-spacing: 0px;
    --text-align: left;
    --min-width: 2rem;
    --max-width: 6rem;    
}
						

Dialog color scheme

The default color palette for the component uses a dark mode theme. You can use CSS to override the variables' defaults:

rwt-file-tabs {
    --color: var(--white);
    --accent-color1: var(--pure-white);
    --background: var(--black);
    --accent-background1: var(--pure-black);
    --accent-background2: var(--nav-black);
    --accent-background3: var(--medium-black);
    --accent-background4: var(--gray);
}
						

Vertically oriented tabs

The component can be oriented vertically by wrapping it in a positioned element and using a CSS transform. Here's an example of how to do it:

HTML

<div id=viewtabs-area>         
    <rwt-file-tabs id=viewtabs scroll-side=left anchor-side=right>
        <button id=id4 slot=tabitem title='Delta view'>Delta</button>
        <button id=id3 slot=tabitem title='Gamma view'>Gamma</button>
        <button id=id2 slot=tabitem title='Beta view'>Beta</button>
        <button id=id1 slot=tabitem title='Alpha view'>Alpha</button>
    </rwt-file-tabs>
</div>
						

CSS

div#viewtabs-area {
    position: absolute;
    top: 2.3rem;
    left: 0;
    bottom: 0;
    width: 2.0rem;
    border-top: 1px solid #000;
    border-bottom: 1px solid #000;
}
#viewtabs {
    position: absolute;
    transform: rotate(-90deg);
    transform-origin: left top;
    width: 34rem; /* JavaScript will override */
    top: 34rem;   /* JavaScript will override */
}
						

JavaScript

function onResize() {
    var viewTabsArea = document.getElementById('viewtabs-area');
    var viewTabs = document.getElementById('viewtabs');
    var height = viewTabsArea.offsetHeight;
    viewTabs.style.width = `${height}px`;
    viewTabs.style.top = `${height}px`;
}

window.addEventListener('resize', onResize);
						

License

The rwt-file-tabs web component is licensed under the MIT License.

MIT License

Copyright © 2020 Read Write Tools.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Availability

Source code	github
Package installation	NPM
Documentation	Read Write Hub