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| 'use strict'
setDOM.KEY = 'data-key'
setDOM.IGNORE = 'data-ignore'
setDOM.CHECKSUM = 'data-checksum'
var parseHTML = require('./parse-html')
var KEY_PREFIX = '_set-dom-'
var NODE_MOUNTED = KEY_PREFIX + 'mounted'
var MOUNT_EVENT = 'mount'
var DISMOUNT_EVENT = 'dismount'
var ELEMENT_TYPE = window.Node.ELEMENT_NODE
var DOCUMENT_TYPE = window.Node.DOCUMENT_NODE
// Expose api.
module.exports = setDOM
/**
* @description
* Updates existing dom to match a new dom.
*
* @param {Node} prev - The html entity to update.
* @param {String|Node} next - The updated html(entity).
*/
function setDOM (prev, next) {
// Ensure a realish dom node is provided.
assert(prev && prev.nodeType, 'You must provide a valid node to update.')
// Alias document element with document.
if (prev.nodeType === DOCUMENT_TYPE) prev = prev.documentElement
// If a string was provided we will parse it as dom.
if (typeof next === 'string') next = parseHTML(next, prev.nodeName)
// Update the node.
setNode(prev, next)
// Trigger mount events on initial set.
if (!prev[NODE_MOUNTED]) {
prev[NODE_MOUNTED] = true
dispatch(prev, MOUNT_EVENT)
}
}
/**
* @private
* @description
* Updates a specific htmlNode and does whatever it takes to convert it to another one.
*
* @param {Node} prev - The previous HTMLNode.
* @param {Node} next - The updated HTMLNode.
*/
function setNode (prev, next) {
if (prev.nodeType === next.nodeType) {
// Handle regular element node updates.
Eif (prev.nodeType === ELEMENT_TYPE) {
// Ignore elements if their checksum matches.
Iif (getCheckSum(prev) === getCheckSum(next)) return prev
// Ignore elements that explicity choose not to be diffed.
Iif (isIgnored(prev) && isIgnored(next)) return prev
// Update all children (and subchildren).
setChildNodes(prev, next)
// Update the elements attributes / tagName.
if (prev.nodeName === next.nodeName) {
// If we have the same nodename then we can directly update the attributes.
setAttributes(prev, prev.attributes, next.attributes)
return prev
} else {
// Otherwise clone the new node to use as the existing node.
var newPrev = next.cloneNode()
// Copy over all existing children from the original node.
while (prev.firstChild) newPrev.appendChild(prev.firstChild)
// Replace the original node with the new one with the right tag.
prev.parentNode.replaceChild(newPrev, prev)
return newPrev
}
} else {
// Handle other types of node updates (text/comments/etc).
// If both are the same type of node we can update directly.
if (prev.nodeValue !== next.nodeValue) {
prev.nodeValue = next.nodeValue
}
return prev
}
} else {
// we have to replace the node.
dispatch(prev, DISMOUNT_EVENT)
prev.parentNode.replaceChild(next, prev)
dispatch(next, MOUNT_EVENT)
return next
}
}
/**
* @private
* @description
* Utility that will update one list of attributes to match another.
*
* @param {Node} parent - The current parentNode being updated.
* @param {NamedNodeMap} prev - The previous attributes.
* @param {NamedNodeMap} next - The updated attributes.
*/
function setAttributes (parent, prev, next) {
var i, a, b, ns, name
// Remove old attributes.
for (i = prev.length; i--;) {
a = prev[i]
ns = a.namespaceURI
name = a.localName
b = next.getNamedItemNS(ns, name)
Eif (!b) prev.removeNamedItemNS(ns, name)
}
// Set new attributes.
for (i = next.length; i--;) {
a = next[i]
ns = a.namespaceURI
name = a.localName
b = prev.getNamedItemNS(ns, name)
Eif (!b) {
// Add a new attribute.
next.removeNamedItemNS(ns, name)
prev.setNamedItemNS(a)
} else if (b.value !== a.value) {
// Update existing attribute.
b.value = a.value
}
}
}
/**
* @private
* @description
* Utility that will nodes childern to match another nodes children.
*
* @param {Node} prevParent - The existing parent node.
* @param {Node} nextParent - The new parent node.
*/
function setChildNodes (oldParent, newParent) {
var curKey, checkKey, seenNodes, checkNode, foundNode
var oldNode = oldParent.firstChild
var newNode = newParent.firstChild
var nextToCheck = oldNode
var nextSibling = newNode
// Loop over new nodes and perform updates.
while (nextSibling) {
newNode = nextSibling
curKey = getKey(newNode)
nextSibling = newNode.nextSibling
Iif (curKey) {
// Try looking up key in previous node key cache.
foundNode = seenNodes && seenNodes[curKey]
// Start looking further in the previous nodelist.
if (!foundNode) {
console.log('looking for', curKey)
while (nextToCheck) {
checkNode = nextToCheck
checkKey = getKey(checkNode)
nextToCheck = nextToCheck.nextSibling
console.log('check', checkNode.nodeName, checkKey)
if (checkKey) {
if (checkKey === curKey) {
console.log('found the key', checkNode.nodeName)
// Store the node to be moved below.
foundNode = checkNode
break
} else {
console.log('found a key to cache', checkNode.nodeName)
seenNodes = seenNodes || {}
seenNodes[checkKey] = checkNode
}
}
}
}
if (foundNode) {
// Check to see if the node is already in the proper place.
if (foundNode !== oldNode) {
console.log('move', foundNode.nodeName, 'to before', oldNode.nodeName)
// If the node is out of place we move it.
oldParent.insertBefore(foundNode, oldNode)
}
// And update the existing node
newNode = setNode(foundNode, newNode)
} else {
// Otherwise we insert the new node here.
oldParent.insertBefore(dispatch(newNode, MOUNT_EVENT), oldNode)
}
} else {
if (oldNode) {
checkNode = oldNode
checkKey = getKey(checkNode)
nextToCheck = oldNode = checkNode.nextSibling
Iif (checkKey) {
// If we got a keyed node we do nothing but track it.
seenNodes = seenNodes || {}
seenNodes[checkKey] = checkNode
oldParent.insertBefore(newNode, checkKey)
dispatch(newNode, MOUNT_EVENT)
} else {
// Otherwise we diff the two unkeyed nodes.
setNode(oldNode, newNode)
}
oldNode = nextToCheck
} else {
nextToCheck = null
oldParent.appendChild(newNode)
dispatch(newNode, MOUNT_EVENT)
}
}
}
// If we have any remaining remove them from the end.
while (nextToCheck) {
console.log('remove', nextToCheck.nodeName)
checkNode = nextToCheck
nextToCheck = checkNode.nextSibling
oldParent.removeChild(checkNode)
}
}
/**
* @private
* @description
* Utility to try to pull a key out of an element.
* Uses 'data-key' if possible and falls back to 'id'.
*
* @param {Node} node - The node to get the key for.
* @return {String}
*/
function getKey (node) {
if (node.nodeType !== ELEMENT_TYPE) return
var key = node.getAttribute(setDOM.KEY) || node.id
if (key) return KEY_PREFIX + key
}
/**
* @private
* @description
* Utility to try to pull a checksum attribute from an element.
* Uses 'data-checksum' or user specified checksum property.
*
* @param {Node} node - The node to get the checksum for.
* @return {String|NaN}
*/
function getCheckSum (node) {
return node.getAttribute(setDOM.CHECKSUM) || NaN
}
/**
* @private
* @description
* Utility to try to check if an element should be ignored by the algorithm.
* Uses 'data-ignore' or user specified ignore property.
*
* @param {Node} node - The node to check if it should be ignored.
* @return {Boolean}
*/
function isIgnored (node) {
return node.getAttribute(setDOM.IGNORE) != null
}
/**
* Recursively trigger an event for a node and it's children.
* Only emits events for keyed nodes.
*
* @param {Node} node - the initial node.
*/
function dispatch (node, type) {
// Trigger event for this element if it has a key.
if (getKey(node)) {
var ev = document.createEvent('Event')
var prop = { value: node }
ev.initEvent(type, false, false)
Object.defineProperty(ev, 'target', prop)
Object.defineProperty(ev, 'srcElement', prop)
node.dispatchEvent(ev)
}
// Dispatch to all children.
var child = node.firstChild
while (child) child = dispatch(child, type).nextSibling
return node
}
/**
* @private
* @description
* Confirm that a value is truthy, throws an error message otherwise.
*
* @param {*} val - the val to test.
* @param {String} msg - the error message on failure.
* @throws Error
*/
function assert (val, msg) {
if (!val) throw new Error('set-dom: ' + msg)
}
|