mirror of https://github.com/n2geoff/um
227 lines
8.8 KiB
JavaScript
227 lines
8.8 KiB
JavaScript
/*! Emerj v1.0.0 | MIT LICENSE | https://github.com/bryhoyt/emerj */
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var diff = {
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attrs(elem) {
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const attrs = {};
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for (let i=0; i < elem.attributes.length; i++) {
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const attr = elem.attributes[i];
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attrs[attr.name] = attr.value;
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}
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return attrs;
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},
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nodesByKey(parent, makeKey) {
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const map = {};
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for (let j=0; j < parent.childNodes.length; j++) {
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const key = makeKey(parent.childNodes[j]);
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if (key) map[key] = parent.childNodes[j];
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}
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return map;
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},
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merge(base, modified, opts) {
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/* Merge any differences between base and modified back into base.
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*
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* Operates only the children nodes, and does not change the root node or its
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* attributes.
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*
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* Conceptually similar to React's reconciliation algorithm:
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* https://facebook.github.io/react/docs/reconciliation.html
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*
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* I haven't thoroughly tested performance to compare to naive DOM updates (i.e.
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* just updating the entire DOM from a string using .innerHTML), but some quick
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* tests on a basic DOMs were twice as fast -- so at least it's not slower in
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* a simple scenario -- and it's definitely "fast enough" for responsive UI and
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* even smooth animation.
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*
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* The real advantage for me is not so much performance, but that state & identity
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* of existing elements is preserved -- text typed into an <input>, an open
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* <select> dropdown, scroll position, ad-hoc attached events, canvas paint, etc,
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* are preserved as long as an element's identity remains.
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*
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* See https://korynunn.wordpress.com/2013/03/19/the-dom-isnt-slow-you-are/
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*/
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opts = opts || {};
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opts.key = opts.key || (node => node.id);
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if (typeof modified === 'string') {
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const html = modified;
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// Make sure the parent element of the provided HTML is of the same type as
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// `base`'s parent. This matters when the HTML contains fragments that are
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// only valid inside certain elements, eg <td>s, which must have a <tr>
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// parent.
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modified = document.createElement(base.tagName);
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modified.innerHTML = html;
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}
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// Naively recurse into the children, if any, replacing or updating new
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// elements that are in the same position as old, deleting trailing elements
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// when the new list contains fewer children, or appending new elements if
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// it contains more children.
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//
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// For re-ordered children, the `id` attribute can be used to preserve identity.
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// Loop through .childNodes, not just .children, so we compare text nodes (and
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// comment nodes, fwiw) too.
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const nodesByKey = {old: this.nodesByKey(base, opts.key),
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new: this.nodesByKey(modified, opts.key)};
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let idx;
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for (idx=0; modified.firstChild; idx++) {
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const newNode = modified.removeChild(modified.firstChild);
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if (idx >= base.childNodes.length) {
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// It's a new node. Append it.
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base.appendChild(newNode);
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continue;
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}
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let baseNode = base.childNodes[idx];
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// If the children are indexed, then make sure to retain their identity in
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// the new order.
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const newKey = opts.key(newNode);
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if (opts.key(baseNode) || newKey) {
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// If the new node has a key, then either use its existing match, or insert it.
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// If not, but the old node has a key, then make sure to leave it untouched and insert the new one instead.
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// Else neither node has a key. Just overwrite old with new.
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const match = (newKey && newKey in nodesByKey.old)? nodesByKey.old[newKey]: newNode;
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if (match !== baseNode) {
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baseNode = base.insertBefore(match, baseNode);
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}
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}
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if (baseNode.nodeType !== newNode.nodeType || baseNode.tagName !== newNode.tagName) {
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// Completely different node types. Just update the whole subtree, like React does.
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base.replaceChild(newNode, baseNode);
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} else if ([Node.TEXT_NODE, Node.COMMENT_NODE].indexOf(baseNode.nodeType) >= 0) {
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// This is the terminating case of the merge() recursion.
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if (baseNode.textContent === newNode.textContent) continue; // Don't write if we don't need to.
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baseNode.textContent = newNode.textContent;
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} else if (baseNode !== newNode) { // Only need to update if we haven't just inserted the newNode in.
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// It's an existing node with the same tag name. Update only what's necessary.
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// First, make dicts of attributes, for fast lookup:
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const attrs = {base: this.attrs(baseNode), new: this.attrs(newNode)};
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for (const attr in attrs.base) {
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// Remove any missing attributes.
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if (attr in attrs.new) continue;
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baseNode.removeAttribute(attr);
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}
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for (const attr in attrs.new) {
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// Add and update any new or modified attributes.
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if (attr in attrs.base && attrs.base[attr] === attrs.new[attr]) continue;
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baseNode.setAttribute(attr, attrs.new[attr]);
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}
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// Now, recurse into the children. If the only children are text, this will
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// be the final recursion on this node.
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this.merge(baseNode, newNode);
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}
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}
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while (base.childNodes.length > idx) {
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// If base has more children than modified, delete the extras.
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base.removeChild(base.lastChild);
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}
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},
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};
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/*! Um v0.5.0 | MIT LICENSE | https://github.com/n2geoff/um */
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/**
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* App Builder
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*
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* Composes state, actions, view together as
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* mountable ui
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*
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* @param {Object} opts options bag of state, view, actions, and mount
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* @param {Object} opts.state initial app object state
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* @param {Function} opts.view function that returns dom. state and actions are passed in
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* @param {Object} opts.actions object functions includes and return state
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* @param {String} opts.mount querySelector value
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*
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* @returns {Object} state and update() interface
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*/
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function app(opts) {
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// initial setup
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const state = check(opts.state, {});
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const view = check(opts.view, () => null);
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const actions = check(opts.actions, {});
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const mount = opts.mount || "body";
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/**
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* simple type validation check
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*
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* @param {*} value
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* @param {String} type
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* @returns {*}
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*/
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function check(value, type) {
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return typeof value === typeof type ? value : type;
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}
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/**
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* Assigns Dispatch-able Actions into App
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*
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* @param {Object} data state used by actions
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* @param {Object} actions functions that update state
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*/
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function dispatch(data, actions) {
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Object.entries(actions).forEach(([name, action]) => {
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if (typeof action === "function") {
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actions[name] = (...args) => {
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// update date from action return
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Object.assign(state, action(data, ...args));
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// call update
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update();
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};
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}
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});
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update();
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}
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/** update dom */
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const update = () => {
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diff.merge(document.querySelector(mount), view(state, actions));
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};
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// mount view
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if (opts.view && mount) {
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dispatch(state, actions);
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}
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return {state,update}
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}
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/**
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* HTML Tag Scripting Function
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*
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* Generates new DOM element(s) from a tag, attributes
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*
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* @param {String} tag - tag name
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* @param {Object|String|Array} args - attributes, text or array of child elements
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*
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* @returns {HTMLElement} The created DOM element(s)
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*/
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function h(tag, ...args) {
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const el = document.createElement(tag);
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// support all scalar values as TextNodes
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const isScalar = (value) => ["boolean", "string", "number"].includes(typeof value);
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for(let i = 0; i < args.length; i++) {
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if (isScalar(args[i])) {
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el.appendChild(document.createTextNode(args[i]));
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} else if (Array.isArray(args[i])) {
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el.append(...args[i]);
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} else {
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for(const [k,v] of Object.entries(args[i])) {
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// if not both ways, some attributes do not render
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el.setAttribute(k, v);
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el[k] = v;
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}
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}
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}
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return el;
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}
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export { app, h };
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