fix: Improve paste handler parsing for more cases, specifically Google Docs (#3322)

shared/editor/marks/Bold.ts

@@ -4,6 +4,9 @@ import { MarkSpec, MarkType } from "prosemirror-model";
 import markInputRule from "../lib/markInputRule";
 import Mark from "./Mark";
 
+const heavyWeightRegex = /^(bold(er)?|[5-9]\d{2,})$/;
+const normalWeightRegex = /^(normal|[1-4]\d{2,})$/;
+
 export default class Bold extends Mark {
   get name() {
     return "strong";
@@ -11,7 +14,20 @@ export default class Bold extends Mark {
 
   get schema(): MarkSpec {
     return {
-      parseDOM: [{ tag: "b" }, { tag: "strong" }],
+      parseDOM: [
+        {
+          tag: "b",
+          // Google Docs includes <b> tags with font-weight: normal so we need
+          // to account for this case specifically as not becoming bold when pasted.
+          getAttrs: (dom: HTMLElement) =>
+            normalWeightRegex.test(dom.style.fontWeight) ? false : null,
+        },
+        { tag: "strong" },
+        {
+          style: "font-weight",
+          getAttrs: (style: string) => heavyWeightRegex.test(style) && null,
+        },
+      ],
       toDOM: () => ["strong"],
     };
   }

shared/editor/marks/Italic.ts

@@ -12,7 +12,14 @@ export default class Italic extends Mark {
 
   get schema(): MarkSpec {
     return {
-      parseDOM: [{ tag: "i" }, { tag: "em" }],
+      parseDOM: [
+        { tag: "i" },
+        { tag: "em" },
+        {
+          style: "font-style",
+          getAttrs: (value) => (value === "italic" ? null : false),
+        },
+      ],
       toDOM: () => ["em"],
     };
   }

shared/editor/marks/Strikethrough.ts

@@ -20,6 +20,10 @@ export default class Strikethrough extends Mark {
         {
           tag: "strike",
         },
+        {
+          style: "text-decoration",
+          getAttrs: (value) => (value === "line-through" ? null : false),
+        },
       ],
       toDOM: () => ["del", 0],
     };

shared/editor/marks/Underline.ts

@@ -15,7 +15,7 @@ export default class Underline extends Mark {
         { tag: "u" },
         {
           style: "text-decoration",
-          getAttrs: (value) => (value === "underline" ? {} : undefined),
+          getAttrs: (value) => (value === "underline" ? null : false),
         },
       ],
       toDOM: () => ["u", 0],