npm install --save @playframe/shadomimport oversync from '@playframe/oversync'
import h from '@playframe/h'
import shadom from '@playframe/shadom'
const sync = oversync(Date.now, requestAnimationFrame)
const state = {}
const View = (state)=> <div></div> // h('div')
const render = shadom(sync)(document.body)
// to update DOM we do
render(View, state)@playframe/h is required as peer dependency. We are importing
a VNODE
Symbol
constant. Symbol can't be created twice in two different places.
It is important to use the same instance of @playframe/h acroass
your app
{VNODE} = h = require '@playframe/h'
{isArray} = Array
doc = documentLet's remind outselves our virtual dom data structure
['div', {class: 's'}, children...] to clarify the constants.
NAME = 0
ATTR = 1
FIRST_CHILD = 2Symbols are designed to assign metaproperties to existing
objects. Those properties are not occuring in for or Object.keys
iteration. They are also free from name conflicts. For example
different libraries can create own Symbol('ELEMENT') and use them
on the same object without any collision
ELEMENT = Symbol 'ELEMENT'
EVENTS = Symbol 'EVENTS'
KEYED = Symbol 'KEYED'
_sync = null
_first_run = trueThis function will handle event dispatching
eventHandler = (event)=>
event.currentTarget[EVENTS][event.type] event
returnWe are exporting a higher order function that will take sync scheduler
and a root element. It will return a function that takes latest
view function and state and schedules vDOM producing and
DOM mutating
module.exports = (sync)=>(root)=>
_sync = sync
_v_dom = null
_new_v_dom = null
if _dom = root.children[0]
_v_dom = scan _dom
render = =>
_dom = mutate_dom root, _dom, _new_v_dom, _v_dom
_v_dom = _new_v_dom
return
(view, state)=>
_new_v_dom = view state
if _first_run # render asap
do render
_first_run = false
else
_sync.render render
returnReusing preexisting html nodes in root element. This will benefit
apps with server side pre-rendering
scan = (el, NS)=>
NS = el.namespaceURI or NS
if el.nodeType is 3 # text
el.nodeValue
else
v_dom = h el.nodeName.toLowerCase(), null
{childNodes} = if shadow = el.shadowRoot
v_dom.patch = patcher v_dom, el, shadow, NS
shadow
else
el
for i in [0...childNodes.length] by 1
v_dom.push scan childNodes[i]
v_domThis function will take a DOM element el and its parent element.
Also it takes a new vDOM vnode and old_vnode. Their diff will
mutate el. NS is a XMLNS namespace for working with SVG or XHTML
mutate_dom = (parent, el, vnode, old_vnode, NS)=>
# console.log 'mutate_dom', vnode, old_vnode
unless vnode is old_vnode
if old_vnode? and vnode? and not old_vnode[VNODE] and not vnode[VNODE]
el.nodeValue = vnode # text node
else
# for SVG or XHTML
NS = vnode and vnode[ATTR]?.xmlns or NS
if not vnode? or not old_vnode? or old_vnode[NAME] isnt vnode[NAME]
# replace node
if vnode?
new_el = make_el vnode, NS
parent.insertBefore new_el, el
if old_vnode?
remove_el parent, el
_sync.next => emmit_remove old_vnode
return new_el
else # update node
if patch = old_vnode.patch
vnode.patch = patch
patch vnode
else
set_attr el, vnode[ATTR], old_vnode[ATTR], NS
mutate_children el, vnode, old_vnode, NS
if onupdate = vnode[ATTR] and vnode[ATTR][if _first_run
'oncreate'
else 'onupdate'
]
onupdate el
elThis function will compare and mutate children of given el.
Keyed updates are supported
mutate_children = (el, vnode, old_vnode, NS)=>
i = j = FIRST_CHILD
sub_i = sub_j = sub_il = sub_jl = el_i = 0
l = vnode.length
ll = old_vnode?.length or 0
by_key = false
while true
# 2 inline child walkers for performance reasons
# getting next child in ['div', {}, child, [child, child],...]
while i <= l
child = vnode[i]
if not child? or child in [true, false]
i++ # continue
else if child[VNODE] or not isArray child
i++
break
else
sub_il or= child.length
if (sub_child = child[sub_i])? and sub_child not in [true, false]
sub_i++
child = sub_child
break
else
if sub_i < sub_il
sub_i++
else
sub_i = sub_il = 0
i++
key = get_key child
while j <= ll
old_key = null
old_child = old_vnode[j]
if not old_child? or old_child in [true, false]
j++ # continue
else if old_child[VNODE] or not isArray old_child
j++
old_key = get_key old_child
break unless old_keyed and old_key and not old_keyed[old_key]
else
sub_jl or= old_child.length
if (sub_child = old_child[sub_j])? and sub_child not in [true, false]
sub_j++
old_child = sub_child
old_key = get_key old_child
break unless old_keyed and old_key and not old_keyed[old_key]
else
if sub_j < sub_jl
sub_j++
else
sub_j = sub_jl = 0
j++
break unless child? or old_child?
child_el = el.childNodes[el_i]
if not by_key and (key or old_key)
by_key = true # switch to keyed mode
old_keyed = old_vnode and old_vnode[KEYED]
keyed = vnode[KEYED] = Object.create null
unless old_keyed and child and old_key isnt key
# direct mutation unless key mismatch
child_el = mutate_dom el, child_el, child, old_child, NS
else
# if there is key mismatch
# we will replace current dom node
# with an existing keyed or a new one
if replacement = old_keyed[key]
replaced_el = mutate_dom el, replacement[ELEMENT], child, replacement, NS
else
replaced_el = make_el child, NS
el.insertBefore replaced_el, child_el
if old_child
remove_el el, child_el
if old_key
# emit remove if not reused
_sync.render do (old_key)=>=> # old_key closure
if old_keyed[old_key]
emmit_remove old_keyed[old_key]
else
emmit_remove old_child
child_el = replaced_el
if child?
el_i++ # moving pointer to next DOM element
if key
child[ELEMENT] = child_el
keyed[key] = child
old_keyed and old_keyed[key] = null
# end of loop
if old_keyed
# copying over unused cached keyed nodes
for k, v of old_keyed when v
keyed[k] = v
returnThis function will create a new DOM element with its children
make_el = (vnode, NS)=>
if vnode[VNODE]
el = if NS
doc.createElementNS NS, vnode[NAME]
else
doc.createElement vnode[NAME]
set_attr el, vnode[ATTR], null, NS
if shadow_props = vnode[ATTR] and vnode[ATTR].attachShadow
shadow = el.attachShadow shadow_props
vnode.patch = patcher vnode, el, shadow, NS
mutate_children shadow, vnode, null, NS
else
mutate_children el, vnode, null, NS
if oncreate = vnode[ATTR] and vnode[ATTR].oncreate
oncreate el
el
else
doc.createTextNode vnodeRemoving element from its parent
remove_el = (parent, el)=>
parent.removeChild el
return
emmit_remove = (vnode)=>
{length} = vnode
while length-- > 0
if isArray child = vnode[length]
emmit_remove child
if onremove = vnode[ATTR] and vnode[ATTR].onremove
onremove()
returnComparing and setting attributes
set_attr = (el, attr, old_attr, NS)=>
for k, old_v of old_attr when not (attr and attr[k]?)
set el, k, null, old_v, NS
for k, v of attr
old_v = if k in ['value', 'checked']
el[k]
else
old_attr and old_attr[k]
set el, k, v, old_v, NS if v isnt old_v
return
set = (el, name, value, old_value, NS)=>
if name in ['key', 'attachShadow']
# skip
else if name is 'style'
style = el[name]
if typeof value is 'string'
style.cssText = value
else
if typeof old_value is 'string'
style.cssText = ''
else
value = {value...}
for k of old_value
value[k] ?= ''
for k, v of value
if k.charCodeAt(0) is 45 # starts with '-'
style.setProperty k, v
else
style[k] = v
else
# starts with 'on', event listener
if name.charCodeAt(0) is 111 and name.charCodeAt(1) is 110
name = name.slice 2
events = el[EVENTS] or= {}
old_value or= events[name]
events[name] = value
if value
if !old_value
el.addEventListener name, eventHandler
else
el.removeEventListener name, eventHandler
# attribute
else if (name of el and
name not in ['list', 'type', 'draggable', 'spellcheck', 'translate'] and
not NS)
el[name] = value ?= ''
else if value? and value isnt false
el.setAttribute name, value
else
el.removeAttribute name
returnGetting a key from a virtual node
get_key = (vnode)=> vnode and vnode[ATTR] and vnode[ATTR].keyCreating a shadow DOM patch function
patcher = (_old_vnode, el, shadow, NS)=>(vnode)=>
unless vnode is _old_vnode
set_attr el, vnode[ATTR], _old_vnode[ATTR], NS
mutate_children shadow, vnode, _old_vnode, NS
_old_vnode = vnode
return