Initial

resources/app/common/prosemirror/schema/utils.mjs

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+import {mergeObject} from "../../utils/helpers.mjs";
+
+// A list of tag names that are considered allowable inside a node that only supports inline content.
+const INLINE_TAGS = new Set(["A", "EM", "I", "STRONG", "B", "CODE", "U", "S", "DEL", "SUP", "SUB", "SPAN"]);
+
+/**
+ * Determine if an HTML element contains purely inline content, i.e. only text nodes and 'mark' elements.
+ * @param {HTMLElement} element  The element.
+ * @returns {boolean}
+ */
+export function onlyInlineContent(element) {
+  for ( const child of element.children ) {
+    if ( !INLINE_TAGS.has(child.tagName) ) return false;
+  }
+  return true;
+}
+
+/* -------------------------------------------- */
+
+/**
+ * Determine if an HTML element is empty.
+ * @param {HTMLElement} element  The element.
+ * @returns {boolean}
+ */
+export function isElementEmpty(element) {
+  return !element.childNodes.length;
+}
+
+/* -------------------------------------------- */
+
+/**
+ * Convert an element's style attribute string into an object.
+ * @param {string} str  The style string.
+ * @returns {object}
+ */
+export function stylesFromString(str) {
+  return Object.fromEntries(str.split(/;\s*/g).map(prop => prop.split(/:\s*/)));
+}
+
+/* -------------------------------------------- */
+
+/**
+ * Merge two style attribute strings.
+ * @param {string} a  The first style string.
+ * @param {string} b  The second style string.
+ * @returns {string}
+ */
+export function mergeStyle(a, b) {
+  const allStyles = mergeObject(stylesFromString(a), stylesFromString(b));
+  return Object.entries(allStyles).map(([k, v]) => v ? `${k}: ${v}` : null).filterJoin("; ");
+}
+
+/* -------------------------------------------- */
+
+/**
+ * Convert an element's class attribute string into an array of class names.
+ * @param {string} str  The class string.
+ * @returns {string[]}
+ */
+export function classesFromString(str) {
+  return str.split(/\s+/g);
+}
+
+/* -------------------------------------------- */
+
+/**
+ * Merge two class attribute strings.
+ * @param {string} a  The first class string.
+ * @param {string} b  The second class string.
+ * @returns {string}
+ */
+export function mergeClass(a, b) {
+  const allClasses = classesFromString(a).concat(classesFromString(b));
+  return Array.from(new Set(allClasses)).join(" ");
+}