making some good progress

src/util/dom_trickery.ts

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+
+// If there is a caret anywhere in the document (user entering text), returns the position of the caret in the focused element
+export function getCaretPosition(): number | undefined {
+  const selection = window.getSelection();
+  if (selection) {
+    const range = selection.getRangeAt(0);
+    const clonedRange = range.cloneRange();
+    return clonedRange.startOffset;
+  }
+}
+
+// export function setCursorPosition(elem, pos) {
+//   const range = document.createRange();
+//   range.selectNode(elem);
+//   range.setStart(elem, pos);
+//   range.setEnd(elem, pos);
+//   const selection = window.getSelection();
+//   selection?.removeAllRanges();
+//   selection?.addRange(range);
+// }
+
+// Move caret all the way to the right in the currently focused element
+export function setRightMostCaretPosition(elem) {
+  const range = document.createRange();
+  range.selectNode(elem);
+  if (elem.lastChild) { // if no text is entered, there is no lastChild
+    range.setStart(elem.lastChild, elem.textContent.length);
+    range.setEnd(elem.lastChild, elem.textContent.length);
+    const selection = window.getSelection();
+    selection?.removeAllRanges();
+    selection?.addRange(range);
+  }
+}
+
+export function focusNextElement() {
+  const editable = Array.from<any>(document.querySelectorAll('[contenteditable]'));
+  const index = editable.indexOf(document.activeElement);
+  editable[index+1]?.focus();
+}
+
+export function focusPrevElement() {
+  const editable = Array.from<any>(document.querySelectorAll('[contenteditable]'));
+  const index = editable.indexOf(document.activeElement);
+  const prevElem = editable[index-1]
+  if (prevElem) {
+    prevElem.focus();
+    setRightMostCaretPosition(prevElem);
+  }
+}

src/util/extra.ts

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+export interface Dynamic {
+  i: any;
+  t: any;
+}
+
+export interface State2Props<T> {
+  state: T;
+  // setState: (callback: (state: T) => T) => void;
+  setState: (state: T) => void;
+}

src/util/fake_node_util.js

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+// In the browser, we don't use the inspect.custom symbol,
+// but it still needs to exist.
+
+export const inspect = {
+  custom: Symbol(),
+};

src/util/parse.ts

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+
+// Helpers...
+export function parseDouble(text: string): number | undefined {
+  if (text === '') {
+    return;
+  }
+  const num = Number(text);
+  if (Number.isNaN(num)) {
+    return;
+  }
+  return num;
+}
+export function parseInt(text: string): bigint | undefined {
+  if (text === '') {
+    return;
+  }
+  try {
+    return BigInt(text);
+  }
+  catch (e) { };
+}