var applyProperties = require('./lib/apply-properties') var isObservable = require('./is-observable') var parseTag = require('./lib/parse-tag') var walk = require('./lib/walk') var watch = require('./watch') var caches = new global.WeakMap() var bindQueue = [] var currentlyBinding = false var watcher = null var releaseNextTick = require('./lib/release-next-tick') module.exports = function (tag, attributes, children) { return Element(global.document, null, tag, attributes, children) } module.exports.forDocument = function (document, namespace) { return Element.bind(this, document, namespace) } function Element (document, namespace, tagName, properties, children) { if (!children && (Array.isArray(properties) || isText(properties) || isNode(properties) || isObservable(properties))) { children = properties properties = null } checkWatcher(document) properties = properties || {} var tag = parseTag(tagName, properties, namespace) var node = namespace ? document.createElementNS(namespace, tag.tagName) : document.createElement(tag.tagName) if (tag.id) { node.id = tag.id } if (tag.classes && tag.classes.length) { node.className = tag.classes.join(' ') } var data = { targets: new Map(), bindings: [] } caches.set(node, data) applyProperties(node, properties, data) if (children != null) { appendChild(document, node, data, children) } maybeBind(document, node) return node } function appendChild (document, target, data, node) { if (Array.isArray(node)) { node.forEach(function (child) { appendChild(document, target, data, child) }) } else if (isObservable(node)) { var nodes = getNodes(document, resolve(node)) nodes.forEach(append, { target: target, document: document }) data.targets.set(node, nodes) data.bindings.push(new Binding(document, node, data)) } else { node = getNode(document, node) target.appendChild(node) if (getRootNode(node) === document) { walk(node, rebind) } } } function append (child) { this.target.appendChild(child) if (getRootNode(child) === this.document) { walk(child, rebind) } } function maybeBind (document, node) { bindQueue.push([document, node]) if (!currentlyBinding) { currentlyBinding = true setImmediate(flushBindQueue) } } function flushBindQueue () { currentlyBinding = false while (bindQueue.length) { var item = bindQueue.shift() var document = item[0] var node = item[1] if (getRootNode(node) === document) { walk(node, rebind) } } } function checkWatcher (document) { if (!watcher && global.MutationObserver) { watcher = new global.MutationObserver(onMutate) watcher.observe(document, {subtree: true, childList: true}) } } function onMutate (changes) { changes.forEach(handleChange) } function getRootNode (el) { var element = el while (element.parentNode) { element = element.parentNode } return element } function handleChange (change) { for (var i = 0; i < change.addedNodes.length; i++) { // if parent is a mutant element, then safe to assume it has already been bound var node = change.addedNodes[i] if (!caches.has(node.parentNode)) { walk(node, rebind) } } for (var i = 0; i < change.removedNodes.length; i++) { var node = change.removedNodes[i] walk(node, unbind) } } function indexOf (target, item) { return Array.prototype.indexOf.call(target, item) } function replace (oldNodes, newNodes) { var parent = oldNodes[oldNodes.length - 1].parentNode var nodes = parent.childNodes var startIndex = indexOf(nodes, oldNodes[0]) // avoid reinserting nodes that are already in correct position! for (var i = 0; i < newNodes.length; i++) { if (nodes[i + startIndex] === newNodes[i]) { continue } else if (nodes[i + startIndex + 1] === newNodes[i]) { parent.removeChild(nodes[i + startIndex]) continue } else if (nodes[i + startIndex] === newNodes[i + 1] && newNodes[i + 1]) { parent.insertBefore(newNodes[i], nodes[i + startIndex]) } else if (nodes[i + startIndex]) { parent.insertBefore(newNodes[i], nodes[i + startIndex]) } else { parent.appendChild(newNodes[i]) } walk(newNodes[i], rebind) } oldNodes.filter(function (node) { return !~newNodes.indexOf(node) }).forEach(function (node) { if (node.parentNode) { parent.removeChild(node) } walk(node, unbind) }) } function isText (value) { return typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean' } function isNode (value) { // for some reason, img elements are not instances of Node return value instanceof global.Node || (global.HTMLElement && value instanceof global.HTMLElement) } function getNode (document, nodeOrText) { if (nodeOrText == null) { return document.createTextNode('') } else if (isText(nodeOrText)) { return document.createTextNode(nodeOrText.toString()) } else { return nodeOrText } } function getNodes (document, nodeOrNodes) { if (Array.isArray(nodeOrNodes)) { if (nodeOrNodes.length) { var result = [] for (var i = 0; i < nodeOrNodes.length; i++) { var item = nodeOrNodes[i] if (Array.isArray(item)) { getNodes(document, item).forEach(push, result) } else { result.push(getNode(document, item)) } } return result.map(getNode.bind(this, document)) } else { return [getNode(document, null)] } } else { return [getNode(document, nodeOrNodes)] } } function rebind (node) { if (node.nodeType === 1) { var data = caches.get(node) if (data) { data.bindings.forEach(invokeBind) } } } function unbind (node) { if (node.nodeType === 1) { var data = caches.get(node) if (data) { data.bindings.forEach(invokeUnbind) } } } function invokeBind (binding) { binding.bind() } function invokeUnbind (binding) { binding.unbind() } function push (item) { this.push(item) } function resolve (source) { return typeof source === 'function' ? source() : source } function Binding (document, obs, data) { this.document = document this.obs = obs this.data = data this.bound = false this.update = function (value) { var oldNodes = data.targets.get(obs) var newNodes = getNodes(document, value) if (oldNodes) { replace(oldNodes, newNodes) data.targets.set(obs, newNodes) } } // listen immediately, but if not bound before next tick, release this.release = obs(this.update) releaseNextTick(this) } Binding.prototype = { bind: function () { if (!this.bound) { if (!this.release) { this.release = watch(this.obs, this.update) } this.bound = true } }, unbind: function () { if (this.bound) { this.bound = false releaseNextTick(this) } } }