The sidebar navigation uses a jQuery component called Navgoco. The sidebar is a somewhat complex part of the theme that remembers your current page, highlights the active item, stays in a fixed position on the page, and more. This page explains a bit about how the sidebar was put together.
Редактировать

The sidebar uses the Navgoco jQuery plugin as its basis. Why not use Bootstrap? Navgoco provides a few features that I couldn’t find in Bootstrap:

  • Navgoco sets a cookie to remember the user’s position in the sidebar. If you refresh the page, the cookie allows the plugin to remember the state.
  • Navgoco inserts an active class based on the navigation option that’s open. This is essential for keeping the accordion open.
  • Navgoco includes the expand and collapse features of a sidebar.

In short, the sidebar has some complex logic here. I’ve integrated Navgoco’s features with the sidebar.html and sidebar data files to build the sidebar. It’s probably the most impressive part of this theme. (Other themes usually aren’t focused on creating hierarchies of pages, but this kind of hierarchy is important in a documentation site.)

Accordion sidebar feature

The sidebar.html file (inside the _includes folder) contains the .navgoco method called on the #mysidebar element.

There are some options to set within the .navgoco method. The only noteworthy option is accordion. This option makes it so when you expand a section, the other sections collapse. It’s a way of keeping your navigation controls condensed.

The value for accordion is a Boolean (true or false). By default, the accordion option is set as true. If you don’t want the accordion, set it to false. Note that there’s also a block of code near the bottom of sidebar.html that is commented out. Uncomment out that section to have the Collapse all and Expand All buttons appear.

There’s a danger with setting the accordion to false. If you click Expand All and the sidebar expands beyond the dimensions of the browser, users will be stuck. When that happens, it’s hard to collapse it. As a best practice, leave the sidebar’s accordion option set to true.

Fixed position sidebar

The sidebar has one other feature — this one from Bootstrap. If the user’s viewport is tall enough, the sidebar remains fixed on the page. This allows the user to scroll down the page and still keep the sidebar in view.

In the customsscripts.js file in the js folder, there’s a function that adds an affix class if the height of the browser window is greater than 800 pixels. If the browser’s height is less than 800 pixels, the nav affix class does not get inserted. As a result, the sidebar can slide up and down as the user scrolls up and down the page.

Depending on your content, you may need to adjust 800 pixel number. If your sidebar is so long that having it in a fixed position makes it so the bottom of the sidebar gets cut off, increase the 800 pixel number here to a higher number.

In the attributes for each sidebar item, if you use external_url instead of url, the theme will insert the link into an a href element that opens in a blank target.

For example, the sidebar.html file contains the following code:

{% if folderitem.external_url %}
    <li><a href="{{folderitem.external_url}}" target="_blank">{{folderitem.title}}</a></li>```


You can see that the `external_url` is a condition that applies a different formatting. Although this feature is available, I recommend putting any external navigation links in the top navigation bar instead of the side navigation bar.

## Sidebar item highlighting

The sidebar.html file inserts an `active` class into the sidebar element when the `url` attribute in the sidebar data file matches the page URL.

For example, the sidebar.html file contains the following code:


```liquid
{% elsif page.url == folderitem.url %}
   <li class="active"><a href="{{folderitem.url | remove: "/"}}">{{folderitem.title}}</a></li>

If the page.url matches the subfolderitem.url, then an active class gets applied. If not, the active class does not get applied.

The page.url in Jekyll is a site-wide variable. If you insert {{page.url}} on a page, it will render as follows: /mydoc_sidebar_navigation.html. The url attribute in the sidebar item must match the page URL in order to get the active class applied.

This is why the url value in the sidebar data file looks something like this:

    - title: Understanding how the sidebar works
      permalink: mydoc_understand_sidebar.html
      output: web, pdf

Note that the url does not include the project folder where the file is stored. This is because the site uses permalinks, which pulls the topics out of subfolders and places them into the root directory when the site builds.

Now the page.url and the item.url can match and the active class can get applied. With the active class applied, the sidebar section remains open.

Tags: getting_started