##### Open Source DOM Component

The Lineup

All the usual suspects

by Read Write Tools Jan 5, 2020

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Sometimes a visual menu is better than a textual menu.

The rwt-lineup DOM component applies circular styling to
square images, providing a fully iconic interface. For situations where there
are too many hyperlinks to fit in a single line, the extras are kept hidden
until activated by the user, using either the visual pullbar or the component's toggleMenu
method or through its event interface.

This component is a light-hearted take on "The Line Up" of "all the usual
suspects". It's designed for use in a website's top banner area.

The component has these features:

* A single line of icons is displayed in the container's collapsed state. The full
set of icons is display in the expanded state, accommodating any number of menu
items.
* The menu item corresponding to the current page is highlighted and scrolled into
view when the page is loaded.
* The menu has an event interface for expanding and collapsing itself.
* The menu emits a custom event to close sibling menus and dialog boxes.
* Menu items may be kept separate from the DOM component, allowing the webmaster
to change its contents in a single centralized place. Alternatively, menu items
may be slotted directly between the component's opening and closing tags.
* A keyboard listener is provided to allow a shortcut key to expand/collapse the
menu.
* A half-height pullbar for expanding the container is displayed along the bottom
margin, appearing larger on hover.
* The first few times that a visitor interacts with your website, the pullbar
pulses to draw attention to itself.

#### In the wild

To see an example of this component in use, visit the DOPPELMARKS
website. It uses this component at the top of the page. To understand what's
going on under the hood, use the browser's inspector to view the HTML source
code and network activity, and follow along as you read this documentation.

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#### Prerequisites

The rwt-lineup DOM component works in any browser that
supports modern W3C standards. Templates are written using BLUE
PHRASE 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.

#### Download

npm install rwt-lineup
	

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

* Add a script tag to load the component's rwt-lineup.js file:
``html

`

* Add the component tag somewhere on the page.

* For scripting purposes, apply an id attribute.
* Apply a sourceref attribute with a reference to an HTML file containing the
menu's hyperlinks.
* Optionally, apply a shortcut attribute with something like F9, F10, etc. for
hotkey access.
* For WAI-ARIA accessibility apply a role=navigation attribute.
* For simple menus, the sourceref may be omitted and the menu hyperlinks may be
slotted into the DOM component. Simply place the hyperlinks directly between the
and tags.
* Here's an example HTML tag where the menu items are in a separate file:
`html

`


#### Menu template

The content and format of the menu items should follow this pattern, which uses
anchors that enclose images .

`html



`

#### Self identification

The menu item corresponding to the current page can be highlighted when it
identifies itself to the menu. This is accomplished by adding a meta tag to the
page that contains the short-form URL of the page itself. For example, if the
page's full URL is https://example.com:443/services.html the shortform URL would
be /services.html.

The short-form URL should be added to a special-purpose meta tag, like this:

`html

`

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#### Menu item size and spacing

The images that you provide should be square. They will be resized using the
value you specify with the CSS --img-size variable. Spacing between the icons
can be adjusted with the --img-margin variable.

The height of the pullbar can be made more or less prominent by setting the --pullbar-height
variable.

The --width variable can be used to shorten the width of the component's inner
container.

`css
rwt-lineup {
--img-size: 64px;
--img-margin: 16px;
--width: 100%;
--pullbar-height: 1rem;
}
`

#### Menu color scheme

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

`css
rwt-lineup {
--color: var(--pure-white);
--accent-color1: var(--title-blue);
--accent-color2: var(--yellow);
--accent-color3: var(--dark-gray);
--background: var(--transparent-black);
--accent-background1: var(--light-black);
--accent-background2: var(--pure-black);
}
``

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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.

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The menu can be controlled with its event interface.

toggle-lineup

The component listens on DOM document for toggle-lineup messages. Upon receipt it will expand or collapse the lineup.

keydown

The component listens on DOM document for keydown messages. If the user presses the configured shortcut key (F9, F10, etc) it will collapse/expand the menu. The Esc key collapses the menu.

collapse-popup

The component listens on DOM document for collapse-popup messages, which are sent by sibling menus or dialog boxes. Upon receipt it will collapse itself.

click

The component listens on DOM document for click messages. When the user clicks anywhere outside the menu, it collapses itself.

---

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	Documentation	READ WRITE HUB
	Source code	github
	Component catalog	DOM COMPONENTS
	Package installation	npm
	Publication venue	READ WRITE STACK

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The rwt-lineup DOM component is licensed under the MIT
License.