preview view model

src/utils/html.js

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+/*
+Copyright 2020 Bruno Windels <bruno@windels.cloud>
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// DOM helper functions
+
+export function isChildren(children) {
+    // children should be an not-object (that's the attributes), or a domnode, or an array
+    return typeof children !== "object" || !!children.nodeType || Array.isArray(children);
+}
+
+export function classNames(obj, value) {
+    return Object.entries(obj).reduce((cn, [name, enabled]) => {
+        if (typeof enabled === "function") {
+            enabled = enabled(value);
+        }
+        if (enabled) {
+            return cn + (cn.length ? " " : "") + name;
+        } else {
+            return cn;
+        }
+    }, "");
+}
+
+export function setAttribute(el, name, value) {
+    if (name === "className") {
+        name = "class";
+    }
+    if (value === false) {
+        el.removeAttribute(name);
+    } else {
+        if (value === true) {
+            value = name;
+        }
+        el.setAttribute(name, value);
+    }
+}
+
+export function el(elementName, attributes, children) {
+    return elNS(HTML_NS, elementName, attributes, children);
+}
+
+export function elNS(ns, elementName, attributes, children) {
+    if (attributes && isChildren(attributes)) {
+        children = attributes;
+        attributes = null;
+    }
+
+    const e = document.createElementNS(ns, elementName);
+
+    if (attributes) {
+        for (let [name, value] of Object.entries(attributes)) {
+            if (name === "className" && typeof value === "object" && value !== null) {
+                value = classNames(value);
+            }
+            setAttribute(e, name, value);
+        }
+    }
+
+    if (children) {
+        if (!Array.isArray(children)) {
+            children = [children];
+        }
+        for (let c of children) {
+            if (!c.nodeType) {
+                c = text(c);
+            }
+            e.appendChild(c);
+        }
+    }
+    return e;
+}
+
+export function text(str) {
+    return document.createTextNode(str);
+}
+
+export const HTML_NS = "http://www.w3.org/1999/xhtml";
+export const SVG_NS = "http://www.w3.org/2000/svg";
+
+export const TAG_NAMES = {
+    [HTML_NS]: [
+        "br", "a", "ol", "ul", "li", "div", "h1", "h2", "h3", "h4", "h5", "h6",
+        "p", "strong", "em", "span", "img", "section", "main", "article", "aside",
+        "pre", "button", "time", "input", "textarea", "label", "form", "progress", "output"],
+    [SVG_NS]: ["svg", "circle"]
+};
+
+export const tag = {};
+
+
+for (const [ns, tags] of Object.entries(TAG_NAMES)) {
+    for (const tagName of tags) {
+        tag[tagName] = function(attributes, children) {
+            return elNS(ns, tagName, attributes, children);
+        }
+    }
+}