vecty

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 Go to latest Published: Mar 28, 2020 License: BSD-3-Clause Imports: 2 Imported by: 0

README

Vecty is a library for building responsive and dynamic web frontends in Go instead of in JavaScript, HTML & CSS. It competes with modern web frameworks like React & VueJS, and supports compilation to both WebAssembly and vanilla JavaScript.

Build Status GoDoc codecov

Benefits

  • Go developers can be competitive frontend developers.
  • Share Go code between your frontend & backend.
  • Reusability by sharing components via Go packages so that others can simply import them.

Goals

  • Simple
    • Designed from the ground up to be easily mastered by newcomers (like Go).
  • Performant
    • Efficient & understandable performance, small bundle sizes, same performance as raw JS/HTML/CSS.
  • Composable
    • Nest components to form your entire user interface, seperating them logically as you would any normal Go package.
  • Designed for Go (implicit)
    • Written from the ground up asking the question "What is the best way to solve this problem in Go?", not simply asking "How do we translate $POPULAR_LIBRARY to Go?"

Features

  • Compiles to WebAssembly (via standard Go compiler) and vanilla JavaScript (via GopherJS).
  • Small bundle sizes: 0.5 MB hello world (see section below).
  • Fast expectation-based browser DOM diffing ('virtual DOM', but less resource usage).

Current Status

Vecty is currently considered to be an experimental work-in-progress. Prior to widespread production use, we must meet our v1.0.0 milestone goals, which are being completed slowly and steadily as contributors have time (Vecty is over 4 years in the making!).

Early adopters may make use of it for real applications today as long as they are understanding and accepting of the fact that:

  • APIs will change (maybe extensively).
  • A number of important things are not ready:
    • Extensive documentation, examples and tutorials
    • URL-based component routing
    • Ready-to-use component libraries (e.g. material UI)
    • Server-side rendering
    • And more, see milestone: v1.0.0
  • The scope of Vecty is only ~80% defined currently.
  • There are a number of important open issues.

For a list of projects currently using Vecty, see the doc/projects-using-vecty.md file.

Small bundle sizes

Vecty uses extremely minimal dependencies and prides itself on producing very small bundle sizes (mostly limited by the compiler), making it suitable for modern web development:

Example Compiler Bundle size Compressed (gzip)
hellovecty Go + WebAssembly 2.3 MB 0.5 MB
markdown Go + WebAssembly 4.2 MB 0.9 MB
todomvc Go + WebAssembly 3.4 MB 0.7 MB
hellovecty GopherJS 0.5 MB 0.1 MB
markdown GopherJS 2.6 MB 0.4 MB
todomvc GopherJS 1.7 MB 0.3 MB

Community

Changelog

See the doc/CHANGELOG.md file.

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func AddStylesheet 

func AddStylesheet(url string)

AddStylesheet adds an external stylesheet to the document.

func RenderBody 

func RenderBody(body Component)

RenderBody renders the given component as the document body. The given Component's Render method must return a "body" element or a panic will occur.

This function blocks forever in order to prevent the program from exiting, which would prevent components from rerendering themselves in the future.

It is a short-handed form for writing: 

err := vecty.RenderInto("body", body)
if err !== nil {
	panic(err)
}
select{} // run Go forever

func RenderInto 

func RenderInto(selector string, c Component) error

RenderInto renders the given component into the existing HTML element found by the CSS selector (e.g. "#id", ".class-name") by replacing it.

If there is more than one element found, the first is used. If no element is found, an error of type InvalidTargetError is returned.

If the Component's Render method does not return an element of the same type, an error of type ElementMismatchError is returned.

func RenderIntoNode 

func RenderIntoNode(node SyscallJSValue, c Component) error

RenderIntoNode renders the given component into the existing HTML element by replacing it.

If the Component's Render method does not return an element of the same type, an error of type ElementMismatchError is returned.

func Rerender 

func Rerender(c Component)

Rerender causes the body of the given Component (i.e. the HTML returned by the Component's Render method) to be re-rendered.

If the Component has not been rendered before, Rerender panics. If the Component was previously unmounted, Rerender is no-op.

Rerender operates efficiently by batching renders together. As a result, there is no guarantee that a calls to Rerender will map 1:1 with calls to the Component's Render method. For example, two calls to Rerender may result in only one call to the Component's Render method.

func SetTitle 

func SetTitle(title string)

SetTitle sets the title of the document.

Types

type Applyer 

type Applyer interface {
	// Apply applies the markup to the given HTML element or text node.
	Apply(h *HTML)
}

Applyer represents some type of markup (a style, property, data, etc) which can be applied to a given HTML element or text node.

func Attribute 

func Attribute(key string, value interface{}) Applyer

Attribute returns an Applyer which applies the given attribute to an element.

In most situations, you should use Property function, or the prop subpackage (which is type-safe) instead. There are only a few attributes (aria-*, role, etc) which do not have equivalent properties. Always opt for the property first, before relying on an attribute.

func Class 

func Class(class ...string) Applyer

Class returns an Applyer which applies the provided classes. Subsequent calls to this function will append additional classes. To toggle classes, use ClassMap instead. Each class name must be passed as a separate argument.

func Data 

func Data(key, value string) Applyer

Data returns an Applyer which applies the given data attribute.

func Key 

func Key(key interface{}) Applyer

Key returns an Applyer that uniquely identifies the HTML element amongst its siblings. When used, all other sibling elements and components must also be keyed.

func MarkupIf 

func MarkupIf(cond bool, markup ...Applyer) Applyer

MarkupIf returns nil if cond is false, otherwise it returns the given markup.

func Namespace 

func Namespace(uri string) Applyer

Namespace is Applyer which sets the namespace URI to associate with the created element. This is primarily used when working with, e.g., SVG.

See https://developer.mozilla.org/en-US/docs/Web/API/Document/createElementNS#Valid Namespace URIs

func Property 

func Property(key string, value interface{}) Applyer

Property returns an Applyer which applies the given JavaScript property to an HTML element or text node. Generally, this function is not used directly but rather the prop and style subpackages (which are type safe) should be used instead.

To set style, use style package or Style. Property panics if key is "style".

func Style 

func Style(key, value string) Applyer

Style returns an Applyer which applies the given CSS style. Generally, this function is not used directly but rather the style subpackage (which is type safe) should be used instead.

func UnsafeHTML 

func UnsafeHTML(html string) Applyer

UnsafeHTML is Applyer which unsafely sets the inner HTML of an HTML element.

It is entirely up to the caller to ensure the input HTML is properly sanitized.

It is akin to innerHTML in standard JavaScript and dangerouslySetInnerHTML in React, and is said to be unsafe because Vecty makes no effort to validate or ensure the HTML is safe for insertion in the DOM. If the HTML came from a user, for example, it would create a cross-site-scripting (XSS) exploit in the application.

The returned Applyer can only be applied to HTML, not vecty.Text, or else a panic will occur.

type ClassMap 

type ClassMap map[string]bool

ClassMap is markup that specifies classes to be applied to an element if their boolean value are true.

func (ClassMap) Apply 

func (m ClassMap) Apply(h *HTML)

Apply implements the Applyer interface.

type Component 

type Component interface {
	// Render is responsible for building HTML which represents the component.
	//
	// If Render returns nil, the component will render as nothing (in reality,
	// a noscript tag, which has no display or action, and is compatible with
	// Vecty's diffing algorithm).
	Render() ComponentOrHTML

	// Context returns the components context, which is used internally by
	// Vecty in order to store the previous component render for diffing.
	Context() *Core
	// contains filtered or unexported methods
}

Component represents a single visual component within an application. To define a new component simply implement the Render method and embed the Core struct: 

type MyComponent struct {
	vecty.Core
	... additional component fields (state or properties) ...
}

func (c *MyComponent) Render() vecty.ComponentOrHTML {
	... rendering ...
}

type ComponentOrHTML 

type ComponentOrHTML interface {
	// contains filtered or unexported methods
}

ComponentOrHTML represents one of: 

Component
*HTML
List
KeyedList
nil

An unexported method on this interface ensures at compile time that the underlying value must be one of these types.

type Copier 

type Copier interface {
	// Copy returns a copy of the component.
	Copy() Component
}

Copier is an optional interface that a Component can implement in order to copy itself. Vecty must internally copy components, and it does so by either invoking the Copy method of the Component or, if the component does not implement the Copier interface, a shallow copy is performed.

type Core 

type Core struct {
	// contains filtered or unexported fields
}

Core implements the Context method of the Component interface, and is the core/central struct which all Component implementations should embed.

func (*Core) Context 

func (c *Core) Context() *Core

Context implements the Component interface.

type ElementMismatchError 

type ElementMismatchError struct {
	// contains filtered or unexported fields
}

ElementMismatchError is returned when the element returned by a component does not match what is required for rendering.

func (ElementMismatchError) Error 

func (e ElementMismatchError) Error() string

type Event 

type Event struct {
	Value  SyscallJSValue
	Target SyscallJSValue
}

Event represents a DOM event.

type EventListener 

type EventListener struct {
	Name     string
	Listener func(*Event)
	// contains filtered or unexported fields
}

EventListener is markup that specifies a callback function to be invoked when the named DOM event is fired.

func (*EventListener) Apply 

func (l *EventListener) Apply(h *HTML)

Apply implements the Applyer interface.

func (*EventListener) PreventDefault 

func (l *EventListener) PreventDefault() *EventListener

PreventDefault prevents the default behavior of the event from occurring.

See https://developer.mozilla.org/en-US/docs/Web/API/Event/preventDefault.

func (*EventListener) StopPropagation 

func (l *EventListener) StopPropagation() *EventListener

StopPropagation prevents further propagation of the current event in the capturing and bubbling phases.

See https://developer.mozilla.org/en-US/docs/Web/API/Event/stopPropagation.

type HTML 

type HTML struct {
	// contains filtered or unexported fields
}

HTML represents some form of HTML: an element with a specific tag, or some literal text (a TextNode).

func Tag 

func Tag(tag string, m ...MarkupOrChild) *HTML

Tag returns an HTML element with the given tag name. Generally, this function is not used directly but rather the elem subpackage (which is type safe) is used instead.

func Text 

func Text(text string, m ...MarkupOrChild) *HTML

Text returns a TextNode with the given literal text. Because the returned HTML represents a TextNode, the text does not have to be escaped (arbitrary user input fed into this function will always be safely rendered).

func (*HTML) Key 

func (h *HTML) Key() interface{}

Key implements the Keyer interface.

func (*HTML) Node 

func (h *HTML) Node() SyscallJSValue

Node returns the underlying JavaScript Element or TextNode.

It panics if it is called before the DOM node has been attached, i.e. before the associated component's Mounter interface would be invoked.

type InvalidTargetError 

type InvalidTargetError struct {
	// contains filtered or unexported fields
}

InvalidTargetError is returned when the element targeted by a render is invalid because it is null or undefined.

func (InvalidTargetError) Error 

func (e InvalidTargetError) Error() string

type KeyedList 

type KeyedList struct {
	// contains filtered or unexported fields
}

KeyedList is produced by calling List.WithKey. It has no public behaviour, and List members are no longer accessible once wrapped in this stucture.

func (KeyedList) Key 

func (l KeyedList) Key() interface{}

Key implements the Keyer interface

type Keyer 

type Keyer interface {
	// Key returns a value that uniquely identifies the component amongst its
	// siblings. The returned type must be a valid map key, or rendering will
	// panic.
	Key() interface{}
}

Keyer is an optional interface that a Component can implement in order to uniquely identify the component amongst its siblings. If implemented, all siblings, both components and HTML, must also be keyed.

Implementing this interface allows siblings to be removed or re-ordered whilst retaining state, and improving render efficiency.

type List 

type List []ComponentOrHTML

List represents a list of components or HTML.

func (List) WithKey 

func (l List) WithKey(key interface{}) KeyedList

WithKey wraps the List in a Keyer using the given key. List members are inaccessible within the returned value.

type MarkupList 

type MarkupList struct {
	// contains filtered or unexported fields
}

MarkupList represents a list of Applyer which is individually applied to an HTML element or text node.

It may only be created through the Markup function.

func Markup 

func Markup(m ...Applyer) MarkupList

Markup wraps a list of Applyer which is individually applied to an HTML element or text node.

func (MarkupList) Apply 

func (m MarkupList) Apply(h *HTML)

Apply implements the Applyer interface.

type MarkupOrChild 

type MarkupOrChild interface {
	// contains filtered or unexported methods
}

MarkupOrChild represents one of: 

Component
*HTML
List
KeyedList
nil
MarkupList

An unexported method on this interface ensures at compile time that the underlying value must be one of these types.

func If 

func If(cond bool, children ...ComponentOrHTML) MarkupOrChild

If returns nil if cond is false, otherwise it returns the given children.

type Mounter 

type Mounter interface {
	// Mount is called after the component has been mounted, after the DOM node
	// has been attached.
	Mount()
}

Mounter is an optional interface that a Component can implement in order to receive component mount events.

type RenderSkipper 

type RenderSkipper interface {
	// SkipRender is called with a copy of the Component made the last time its
	// Render method was invoked. If it returns true, rendering of the
	// component will be skipped.
	//
	// The previous component may be of a different type than this
	// RenderSkipper itself, thus a type assertion should be used and no action
	// taken if the type does not match.
	SkipRender(prev Component) bool
}

RenderSkipper is an optional interface that Component's can implement in order to short-circuit the reconciliation of a Component's rendered body.

This is purely an optimization, and does not need to be implemented by Components for correctness. Without implementing this interface, only the difference between renders will be applied to the browser DOM. This interface allows components to bypass calculating the difference altogether and quickly state "nothing has changed, do not re-render".

type SyscallJSValue 

type SyscallJSValue jsObject

SyscallJSValue is an actual syscall/js.Value type under WebAssembly and GopherJS compilation.

It is declared here just for purposes of testing Vecty under native 'go test', linting, and serving documentation under godoc.org.

type Unmounter 

type Unmounter interface {
	// Unmount is called before the component has been unmounted, before the
	// DOM node has been removed.
	Unmount()
}

Unmounter is an optional interface that a Component can implement in order to receive component unmount events.

Source Files

View all Source files

Directories

Path Synopsis
Package elem defines markup to create DOM elements.
 Package elem defines markup to create DOM elements.
Package event defines markup to bind DOM events.
 Package event defines markup to bind DOM events.
example module

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