Quick reference guides for languages, frameworks, and technologies.
CSS properties, selectors, and browser compatibility reference.
Elixir language and standard library reference.
HTML element and attribute reference.
Java language and standard library reference.
JavaScript language and browser API reference.
Phoenix web framework and LiveView reference — routing, controllers, views, channels, and real-time LiveView
Preact library reference — lightweight React alternative with the same API.
Python language and standard library reference.
React library reference — components, hooks, and patterns.
Ruby language and standard library reference.
Rust language and standard library reference.
Sass and SCSS reference.
CSS properties, selectors, and browser compatibility reference.
Not all browsers are made the same, browser fallbacks are a big part of css
Reference for CSS layout — flexbox, grid, positioning, and responsive patterns.
Complete reference for CSS selectors — combinators, pseudo-classes, pseudo-elements, and specificity.
Elixir language and standard library reference.
Elixir lists, tuples, maps, keyword lists, MapSets, and Enum functions
Elixir concurrency primitives — Task for async work, Agent for simple state, ETS for in-memory key-value storage
Elixir conditionals — if, unless, case, cond, with, and try/rescue
Elixir Date, Time, DateTime, NaiveDateTime, and Duration handling
Elixir Enum and Stream functions for iterating, mapping, filtering, and reducing collections
Elixir error handling with ok/error tuples, exceptions, try/rescue, and custom errors
Elixir file operations, path manipulation, and IO (input/output) handling
Elixir Mix build tool, project structure, dependencies, tasks, and configuration
Elixir modules, named functions, anonymous functions, defaults, and guards
Elixir OTP behaviours — GenServer, Supervisor, Agent, and Task for building reliable concurrent systems
Elixir pattern matching with = operator, tuples, lists, maps, and case/with
Elixir processes, spawn, send/receive, links, monitors, and the actor model
Elixir strings, charlists, string functions, interpolation, and binary manipulation
Elixir structs for typed data and protocols for polymorphism
Elixir basic types, type specs, and dialyzer for static type analysis
HTML element and attribute reference.
content is "Inline" except that anchors shouldn't be nested
abbreviation
Indicates an acronym (e.g., WAC, radar, etc.).
information on author
bold font
Base tag for document base URI references.
I18N BiDi over-ride
bigger font
forced line break
Content is "Flow" excluding a, form and form controls
Contains a citation or a reference to other sources.
Designates a fragment of computer code.
col elements define the alignment properties for cells in one or more columns. The width attribute specifies the width of the columns, e.g. width=64 width in screen pixels width=0.5* relative width of 0.5 The span attribute causes the attributes of one col element to apply to more than one column.
colgroup groups a set of col elements. It allows you to group several semantically related columns together.
Indicates that this is the defining instance of the enclosed term.
generic language/style container
Indicates emphasis.
The fieldset element is used to group form fields. Only one legend element should occur in the content and if present should only be preceded by whitespace. NOTE this content model is different from the XHTML 1.0 DTD, closer to the intended content model in HTML4 DTD
Content model that is combined with a single title and an optional base elements in any order.
italic font
usemap points to a map element which may be in this document or an external document, although the latter is not widely supported
form control
Indicates text to be entered by the user.
Each label must not contain more than ONE field Label elements shouldn't be nested.
fieldset label
list item
Relationship values can be used in principle for document specific toolbars/menus when used with the link element in document head e.g. start, contents, previous, next, index, end, help to link to a separate style sheet (rel="stylesheet") to make a link to a script (rel="script") by stylesheets to control how collections of html nodes are rendered into printed documents to make a link to a printable version of this document e.g. a PostScript or PDF version (rel="alternate" media="print")
generic metainformation
alternate content container for non script-based rendering
Ordered (numbered) list
option group
selectable choice
param is used to supply a named property value. In XML it would seem natural to follow RDF and support an abbreviated syntax where the param elements are replaced by attribute value pairs on the object start tag.
content is "Inline" excluding "img|object|big|small|sub|sup"
Indicates an inlined quote
Designates sample output from programs, scripts, etc.
script statements, which may include CDATA sections
option selector
smaller font
generic language/style container
Indicates stronger emphasis.
style info, which may include CDATA sections
subscript
superscript
multi-line text field
The title element is not considered part of the flow of text. It should be displayed, for example as the page header or window title. Exactly one title is required per document.
fixed pitch font
Unordered list
Indicates an instance of a variable or program argument.
JavaScript language and browser API reference.
Not all browsers are made the same, browser fallbacks are a big part of css
Phoenix web framework and LiveView reference — routing, controllers, views, channels, and real-time LiveView
Phoenix authentication with phx.gen.auth, session management, and authorization patterns
Phoenix Channels — real-time pub/sub communication with topics, sockets, and broadcasts
Phoenix controllers — actions, params, responses, plugs, and error handling
Phoenix deployment — releases, environment config, Docker, Heroku, and production setup
Phoenix Ecto — schemas, changesets, queries, migrations, repositories, and context modules
Phoenix LiveView — real-time server-rendered interactive views with mount, handle_event, handle_info, and HEEx templates
Phoenix LiveView function components and live components — attrs, slots, HEEx templates, and stateful components
Phoenix router — scopes, pipelines, resources, verified routes, and helpers
Phoenix testing — controllers, LiveView, channels, and context tests with ExUnit and ConnCase
Preact library reference — lightweight React alternative with the same API.
How to use Preact as a drop-in React replacement and which React libraries work with preact/compat.
Preact Signals — fine-grained reactive state that updates only what changes, without re-rendering entire components.
React library reference — components, hooks, and patterns.
Common React component patterns — composition, render props, HOCs, controlled forms, and error boundaries.
Complete reference for all built-in React hooks — useState, useEffect, useContext, and more.
Ruby language and standard library reference.
Get a subset of items or characters based on a range
Make an array of parts of a string based on a delimiter
Rust language and standard library reference.
Rust vectors, HashMaps, HashSets, slices, and iterators — creating, iterating, and transforming
Rust concurrency patterns — threads, channels, mutex, async/await, tokio, and common patterns
Rust deployment strategies — static binaries, Docker, cross-compilation, systemd, cloud platforms, and CI/CD
Rust error handling with Result, the ? operator, custom error types, thiserror, anyhow, and common patterns
Rust module system, visibility, use statements, crate structure, and Cargo workflow
Rust's Option and Result types for null-safe and error-safe code — pattern matching, combinators, the ? operator, and common patterns
Rust ownership model, borrowing rules, and lifetime annotations explained with examples
Rust structs, enums with data, trait definitions and implementations, and common patterns