EditContext: updateSelection() メソッド

updateSelection(start, end)

<canvas id="editor-canvas"></canvas>

const canvas = document.getElementById("editor-canvas");
const editContext = new EditContext();
canvas.editContext = editContext;
canvas.addEventListener("keydown", (e) => {
  if (e.key == "ArrowLeft") {
    const newPosition = Math.max(editContext.selectionStart - 1, 0);
    if (e.shiftKey) {
      editContext.updateSelection(newPosition, editContext.selectionEnd);
    } else {
      editContext.updateSelection(newPosition, newPosition);
    }
  } else if (e.key == "ArrowRight") {
    const newPosition = Math.min(
      editContext.selectionEnd + 1,
      editContext.text.length,
    );
    if (e.shiftKey) {
      editContext.updateSelection(editContext.selectionStart, newPosition);
    } else {
      editContext.updateSelection(newPosition, newPosition);
    }
  }
  console.log(
    `The new EditContext selection is ${editContext.selectionStart}, ${editContext.selectionEnd}`,
  );
});