mireco
Mireco is an extensible library for user interfaces with no heavy dependencies (especially css).
"The golden teaspoon of date pickers"
- Luke Hodkinson
It intends to be a simple example html implementation of a React
interface that adheres to the
following guidelines:
React Interface Philosophy
- All input props take the form of a singular
value
and onChange
- All components are stateless where practical, following the
Tri-State Value System
- Input's
onChange
is a function callback with the new value
as an argument (consumers do no
direct reading from dom elements with refs) - The
onChange
callback and value
prop both use the same value
format, which is always a
primitive or predefined shape of primitives - For basic use cases, all inputs are expected to be used by Mireco consumers as flat components -
eg. the
Checkbox
component uses a convenience label="label contents"
prop instead of requiring
<Label><Checkbox/> label contents</Label>
Non battle-tested guidelines:
- Existing html properties such as
style
and className
should be passed through - with prefixes
where there are multiple injection points eg. containerStyle
and inputStyle
- The
style
prop refers to the outermost container of a Mireco component. More specific style
overrides are given with explicit references eg. inputStyle
and labelStyle
. Where these
overlap and refer to the same element as the style
prop, they are merged with the more specific
name taking precedent.
HTML Design Philosophy
All Mireco components should be designed with the following in mind:
- No external static file requirements - all images are inline
svg
so they support css styling,
only use native fonts - Adhere to strict html components where reasonable for accessibilty
- Minimal html element hierarchy eg. no enormous chains of
<div>
- Everything should still be usable without any css
- Inputs should still render a basic
html
form
value - All components should work by default on any platform (mobile, desktop)
- All css selectors are namespaced to avoid clashes
- Use native browser focus, and support keyboard navigation with js events
- All size units are in
rem
(except for em
for line-height
s relative to font-size
) - Like normal html form inputs, all form components are rendered as
inline
or inline-block
by
default. For convenience, the Mireco api provides a block version of all inputs by passing a
block
prop - No media queries are used in scaling inputs - they should size to their container and not the
screen, using
flex-basis
to take up multiple rows when necessary - There is no hard coded minimum width for any input
Installation
Install the package from npm:
npm install mireco
Make sure your html document is encoded properly (required by parse-duration
micro symbol):
<html>
<head>
<meta charset="utf-8">
</head>
</html>
Add the component stylesheet:
<link rel="stylesheet" href="node_modules/mireco/dist/mireco-components.css" />
To support inputs that have modal dropdowns, ensure that the body of your document (and any
absolutely positioned content blocks such as modals) all have a padding of at least 15rem
at the
bottom.
Development Setup
Install dependencies for project itself, and watch the project for changes
yarn
yarn watch
Accessing demo page
Follow the instructions found in demo/README.md
.
Components
Check out the API Documentation.
Basic form inputs:
Compound form inputs:
Layout:
Tri-State Values
Having properly bound components in React is tricky when the components that the user needs to
interact with are required to sometimes be in invalid states.
The best example of this is a date selector with a text input component - if a user is typing in a
value of 31/3/2012
, between each keystroke the value when parsed could either be completely
different (31/3
would resolve to the current year) or invalid (31
would be of the current month
which does not necessarily contain 31 days).
Most packages get around this with a variety of strategies that have their own drawbacks:
- Requiring some kind of "commitment" action to the value, for instance typing only highlights a day
on a calendar and the user must click the day to select it (clunky to use and does not report
new values to higher components early enough to integrate well)
- Completely detaching the state from its value prop (so the parent cannot change the value whilst
the user is interacting with the widget)
All Mireco components should instead follow this flow of value update:
- The component always updates its parent when any part of it is changed:
- A value of
undefined
means that a true value
cannot in any way be understood from the
various state contents
- A value of
null
means that the value is explicitly set to nothing - A
true value
(of whatever data type is appropriate for your input, eg. milliseconds integer)
is reported when the value can be parsed with the most generous rules possible (does not have to
be perfect)
- When a Mireco component receives a new
prop value
, it is compared to the current various state contents
. If it has changed:
- If the
prop value
is set to undefined
, do absolutely nothing - If the
prop value
is set to a true value
or null
:
- If this is different from the current parsed
various state contents
:
- Update the
various state contents
to a perfectly formatted representation of the new
prop value
, as this means the parent has explicitly overridden our value
- Otherwise, do nothing as this update was likely initiated by this component itself
- When a Mireco component is blurred:
- If the
prop value
is set to a true value
:
- Set the
various state contents
to a perfectly formatted representation of the prop value
- Otherwise:
- Reset the
various state contents
to defaults
Following this flow, self-initiated updates of value are non destructive to the current state whilst
still allowing the parent to change its value. Also, as undefined
and null
are often
interchangeable you can simply take the given value
onChange
without any validation or workflow
in Mireco consumers.