##### Open Source DOM Component

Sitenav

Website pull-out navigation

by Read Write Tools Dec 10, 2019

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Sometimes you need to provide your website visitors with quick access to a large
quantity of pages without cluttering the main reading area of the page.

The rwt-sitenav DOM component does this by keeping the menu
off the left-hand side of the page until the user needs it. The menu is
activated, sliding over the page content, when the user clicks on the hamburger
menu button. Activation may also be initiated through the component's toggleMenu
method or through its event interface.

The component has these features:

* The hamburger menu button is subtly displayed along the left-hand margin,
appearing brighter on hover.
* The first few times that a visitor interacts with your website, the menu button
pulses to draw attention to itself.
* The menu scrolls vertically, accommodating any number of menu items.
* 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.
* The menu item corresponding to the current page is highlighted and scrolled into
view when the page is first loaded.
* The menu has an event interface for showing and hiding itself.
* The menu emits a custom event to close sibling menus and dialog boxes.
* A keyboard listener is provided to allow a shortcut key to open/close the menu.

#### In the wild

To see an example of this component in use, visit the BLUEFIDDLE
website and press F1 "Menu". 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-sitenav 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-sitenav
	

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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-sitenav.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 text and any CSS it needs.
* 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.
`html

`


#### Menu template

The content and format of the menu is not prescribed. You may add hyperlinks
with formatting that matches your website. Still, one important guideline to
keep in mind is that the text of each menu item should be short so that it
doesn't wrap into multiple lines. If necessary, the width of the panel can be
adjusted using the component's --width CSS variable.

The easiest way to start building your menu is to follow this pattern, which
uses list items li for individual pages, and headings h2 for grouping similar
pages.

`html


Products

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 may be added to any of three special-purpose meta tags, like
this:

`html



`

The three items correspond to the artificial hierarchical depth of the menu
items. When the page is first loaded, the DOM component uses the content
attribute of these meta tags as search terms, looking for the menu item with a
matching anchor href. When found, that menu item is highlighted and scrolled
into view.

The search for a corresponding href is conducted starting with the deepest
level, going from sitenav:level3 to sitenav:level2 to sitenav:level1.

Continuing with the previous example, if the current page is https://example.com:443/services.html
, then this menu item will be highlighted:

`html


Services

`css
rwt-sitenav {
--top: 0;
--bottom: 0;
--width: 15.5rem;
--z-index: 1;
}
`

#### 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-sitenav {
--background: var(--nav-black);
--level1-color: var(--title-blue);
--level2-color: var(--pure-white);
--accent-color: var(--yellow);
--accent-background: 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-sitenav

The component listens on DOM document for toggle-sitenav messages. Upon receipt it will show or hide the menu.

keydown

The component listens on DOM document for keydown messages. If the user presses the configured shortcut key (F9, F10, etc) it will show/hide the menu. The Esc key hides 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 close itself.

click

The component listens on DOM document for click messages. When the user clicks anywhere outside the menu, it closes 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-sitenav DOM component is licensed under the MIT
License.