From c443dd7a32665c67c6730f0099859ee11ecf0395 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Fri, 21 Jun 2019 16:37:29 +0200
Subject: [PATCH] clarify why use a BOM marker for the caret nodes

---
 src/editor/dom.js    |  6 +++---
 src/editor/render.js | 13 ++++++++-----
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/editor/dom.js b/src/editor/dom.js
index 5c873034b2..1b683c2c5e 100644
--- a/src/editor/dom.js
+++ b/src/editor/dom.js
@@ -15,7 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {ZERO_WIDTH_SPACE, isCaretNode} from "./render";
+import {CARET_NODE_CHAR, isCaretNode} from "./render";
 
 export function walkDOMDepthFirst(rootNode, enterNodeCallback, leaveNodeCallback) {
     let node = rootNode.firstChild;
@@ -57,7 +57,7 @@ export function getCaretOffsetAndText(editor, sel) {
 function getCaret(focusNode, focusNodeOffset, focusOffset) {
     let atNodeEnd = focusOffset === focusNode.textContent.length;
     if (focusNode.nodeType === Node.TEXT_NODE && isCaretNode(focusNode.parentElement)) {
-        const zwsIdx = focusNode.nodeValue.indexOf(ZERO_WIDTH_SPACE);
+        const zwsIdx = focusNode.nodeValue.indexOf(CARET_NODE_CHAR);
         if (zwsIdx !== -1 && zwsIdx < focusOffset) {
             focusOffset -= 1;
         }
@@ -120,7 +120,7 @@ function getTextNodeValue(node) {
         // typed in the caret node, so there is now something more in it than the ZWS
         // so filter out the ZWS, and take the typed text into account
         if (nodeText.length !== 1) {
-            return nodeText.replace(ZERO_WIDTH_SPACE, "");
+            return nodeText.replace(CARET_NODE_CHAR, "");
         } else {
             // only contains ZWS, which is ignored, so return emtpy string
             return "";
diff --git a/src/editor/render.js b/src/editor/render.js
index 690851c4ea..9d42bbe947 100644
--- a/src/editor/render.js
+++ b/src/editor/render.js
@@ -33,22 +33,25 @@ function insertAfter(node, nodeToInsert) {
     }
 }
 
-// this is a BOM marker actually
-export const ZERO_WIDTH_SPACE = "\ufeff";
+// Use a BOM marker for caret nodes.
+// On a first test, they seem to be filtered out when copying text out of the editor,
+// but this could be platform dependent.
+// As a precautionary measure, I chose the character that slate also uses.
+export const CARET_NODE_CHAR = "\ufeff";
 // a caret node is a node that allows the caret to be placed
 // where otherwise it wouldn't be possible
 // (e.g. next to a pill span without adjacent text node)
 function createCaretNode() {
     const span = document.createElement("span");
     span.className = "caretNode";
-    span.appendChild(document.createTextNode(ZERO_WIDTH_SPACE));
+    span.appendChild(document.createTextNode(CARET_NODE_CHAR));
     return span;
 }
 
 function updateCaretNode(node) {
     // ensure the caret node contains only a zero-width space
-    if (node.textContent !== ZERO_WIDTH_SPACE) {
-        node.textContent = ZERO_WIDTH_SPACE;
+    if (node.textContent !== CARET_NODE_CHAR) {
+        node.textContent = CARET_NODE_CHAR;
     }
 }