Learn Elm, Safari and Webstorm

elm-ui is a novel iteration on declarative styling where you can use Elm types and functions to define your UI in a declarative way. The novel part is that it does not require you to know CSS to be used, you can start building layouts right away!

You'll learn how to:
- use a declarative mindset for building UIs
- position elements on the screen
- create layouts with rows and columns
- build a form with elm-ui

Elm is a programming language that provides a clean functional syntax for writing HTML web applications. It promises zero runtime exceptions, fast rendering, time-travel debugging, and much more.

Declarative UIs without CSS with elm-ui

Elm is a beginner friendly functional reactive programming language for building web applications. It contains a small but powerful set of language constructs, such as, static types, algebraic data types, immutability, and pure functions. Elm provides and requires the use of a specific architecture that’s well suited for sensible application construction. Elm’s type system and architecture may feel constraining at first, but they ultimately provide the programmer with some neat benefits including comprehensible code, and a much improved refactoring experience.

In this course you will learn the basic fundamentals of Elm so that you can start building applications today.

Start Using Elm to Build Web Applications

screen-reader

Learn the basics of navigating through a web page using VoiceOver on MacOS in Safari.

Navigate a Webpage with VoiceOver in Safari

The Chrome Developer Tools (DevTools for short), are a set of web authoring and debugging tools built into Google Chrome.

chrome-devtools

Using our accessibility auditing toolkit we can find issues concerning landmark regions in our web application.  The react-axe library will report findings in the JavaScript console of the browser.  We could also run the axe browser extension to see the same results.  The tota11y browser extension will annotate any landmark regions on the page and therefore if none are annotated it may indicate that they aren't any (_NOTE: tota11y will only annotate landmark regions using aria roles and not those using HTML5 elements_).  Finally using the VoiceOver Rotor in Safari will show us whatever landmark regions have been defined in the Landmarks menu. 

Test for Landmark Region Accessibility Issues in React

We can find issues with heading levels by utilizing our accessibility auditing tools.  The library react-axe, as well as the browser extension axe, will report any findings concerning heading levels.  The browser extension tota11y will annotate all heading levels on a page and show any in red that have issues.  Finally, we can check the Rotor in VoiceOver in Safari.  The Rotor should have a Headings menu and will list in order all of them that are found on the page.  If headings are missing or inappropriate this will help us find them as well.

Test for Heading Level Accessibility Issues

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Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers. Some elements do not already have some sort of labeling text being displayed visually, such as a `<button>` without descriptive text or an `<icon>` or part of a more complex widget.  Others may have some form of text label but it is not descriptive enough for those who cannot see it.  The addition of an `aria-label` attribute to the element will provide it with an accessible label so that when that element is focused by a screen reader, for instance, a label is read that better describes the element and what a user can expect from it.

Add Accessible Labels to Elements Whose Labels are Not Clear Enough

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers. Some elements do not already have some sort of labeling text being displayed visually, such as a `<button>` without descriptive text or an `<icon>` or part of a more complex widget.  Others may have some form of text label but it does not provide enough context to be useful enough for those that cannot see it.  The addition of an `aria-label` attribute to the element will provide it with an accessible label so that when that element is focused by a screen reader, for instance, a label is read provides better context for the element and what a user can expect from it.

Add Accessible Labels to Provide Elements with More Context

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers.  When there are already one or more other elements that themselves can be used to provide labeling text to another element an `aria-labelledby` attribute can be added to that element.  

Some examples of appropriate use cases for using an `aria-labelledby` are:
* Combine multiple labels together
* Associate headings with regions
* Label for a widget

Add an Accessible Label to an Element from the Text of Other Elements

Labeling inputs, elements, and widgets add context and clarity for assistive technology such as screen readers. Beyond adding accessible labels to elements and widgets we can also provide additional descriptions.  Similar to how an `aria-labelledby` attribute works, an `aria-describedby` attribute can link the text from another element or elements to be used as a description for the given element.  

Some example use cases for using an `aria-describedby` are:
* providing instructions
* providing important usage details

Add Accessible Descriptions to Elements

When dynamic changes occur to content on a page they are usually visually apparent to users who can see the page but may not be made apparent to users of assistive technologies. ARIA live regions provide a way to make those dynamic content changes able to be announced by assistive technologies.

## ARIA attributes
* `aria-live`: the priority with which updates are read
* `aria-atomic`: whether the screen reader should always present the live region as a whole, even if only part of the region changes
* `aria-relevant` - takes a list of what type of changes should be announced

## Resources
* https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/ARIA_Live_Regions
* https://www.w3.org/WAI/PF/aria-1.1/states_and_properties#aria-live
* https://www.w3.org/WAI/PF/aria-1.1/states_and_properties#aria-atomic
* https://www.w3.org/WAI/PF/aria-1.1/states_and_properties#aria-relevant
* http://html.cita.illinois.edu/nav/form/aria/index.php?example=3

Define a Live Region to Ensure Dynamic Changes are Announced by Assistive Technologies

We are going to go ahead and install globally create-elm-app (because it has the best DX so far) and show how would you typically start any production-ready Elm app, and also add elm-ui as a dependency and show the first elements with elm-ui.

Bootstrap an elm-ui Application with create-elm-app

To showcase the power of elm-ui, in this lesson we will show how incredibly easy it is to center an element both horizontally and vertically on a screen with elm-ui, since this is a typical problem while doing regular CSS.

Center an elm-ui Element Horizontally and Vertically

In this lesson we will start to get to know the row and column functions in elm-ui to help us layout our application. We will choose the mobile first approach in which we will display everything in one column, show how to handle two columns and explain that later when we do responsible we will be able to play a bit more with this. Since the concept of margin does not exist in elm-ui, in this lesson we learn how to solve it by using spacing and we will talk about padding in a future lesson.

Model a Layout with row, column and spacing with elm-ui

We will use the pink box element that we had from previous lessons while implementing our fancy dashboard and we will turn it into our Card "component", the piece of UI that we are going to repeat and that will have its own state later on the course. 

To do this, we'll first manipulate the background color and text color, then change the height and width of the card. We will want to change the title for each of the cards and to do so we will accept a title argument that will be passed down to our text element within the card to be displayed.

Use View Functions to Create Reusable Pieces of UI in Elm

Since we mentioned in a previous lesson that there is no concept of "margin" in elm-ui, we are goint to learn how to se `padding`, `paddingXY` and `paddingEach` to compensate for that, and a little trick defining a value edges that is going to be pretty useful.

Use padding, paddingXY and paddingEach with elm-ui

We will style the heading of `viewCards` to look more like a real heading. If you inspect the console right now, you'll find that the `el` element we are using for our text corresponds to a div in HTML. 

We will go further away than using only text to display our content and introduce the modules `Element.Font` and `Element.Region` to fix the headlines and other text of our dashboard, adding an additional "breakdown" heading that is going to serve as a divider between sections.

Style Text with elm-ui Headlines, Typographies, and Fonts

In this lesson, we will explain when you would need to reach for the `text` function, why it is different from `textColumn` and `paragraph` and when to use each one as they serve different purposes for displaying text in the UI. Basically, `el` and `text` elements **do not wrap text by default**, so we need to use `paragraph` when we want text to overflow and still be visible to read. We will add a new "subtitle" section below our Breakdown subheading

Choose between text, textColumn and paragraph with elm-ui

Now that we have our cards more or less looking good lets add a button and style it as well so that it serves as a starting point for our dropdown component, this lesson will also help us to learn how to use the `Element.Input` module from elm-ui.

Work with elm-ui Input Components

Since there is no select or dropdown component backed in into elm-ui, we will be adding another dependency to our project called `PaackEng/elm-ui-dropdown` and adding to it additional styles and settings so that it looks and behaves exactly as we want to.

To make this works, we need to make a few changes:
- We need to add a `dropdownState : Dropdown.State String` to our `Model`
- Add a couple of extra variants to our `Msg` type: `OptionPicked (Maybe String)`, to be dispatched by our dropdown whenever we click on any option, and `DropdownMsg (Dropdown.Msg String)` to update the internal state of the dropdown from the outside.
- Construct our hardcoded list of options of type `List String`.
- Define a `dropdownConfig : Dropdown.Config String Msg` that is going to contain all our customisation of our dropdown.
- Use `Dropdown.view` to display our custom dropdown wherever we need it.

Customize My Own Dropdown with elm-ui-dropdown

Now that our dropdown is almost finished lets just drop some shadow in the options selector to make it more visually clear that its over any other element in our page. This is an attribute that we can control the `offset`, `size`, `blur`, and `color`.

We will want to do this to our `viewCard` as well. We will also make the `viewCard` function more flexible by adding additional `Html` attributes from the outside to make each card have a different **height.** That way any time you want to override default attributes, you can pass in a new style.

Add elm-ui Border.shadow to Highlight Any Element

This is the only lesson in which we will fallback to CSS to give our dropdown's scrollbar a fancier look because this is very browser dependent and there is no way (yet) to do this with elm-ui.

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