Use fromCodePoint to convert high value unicode entities

src/plugins/jsx/fromCodePoint.js

@@ -0,0 +1,66 @@
+// Adapted from String.fromcodepoint to export the function without modifying String
+/*! https://mths.be/fromcodepoint v0.2.1 by @mathias */
+
+// The MIT License (MIT)
+// Copyright (c) Mathias Bynens
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+// associated documentation files (the "Software"), to deal in the Software without restriction,
+// including without limitation the rights to use, copy, modify, merge, publish, distribute,
+// sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+// NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+let fromCodePoint = String.fromCodePoint;
+
+if (!fromCodePoint) {
+  const stringFromCharCode = String.fromCharCode;
+  const floor = Math.floor;
+  fromCodePoint = function() {
+    const MAX_SIZE = 0x4000;
+    const codeUnits = [];
+    let highSurrogate;
+    let lowSurrogate;
+    let index = -1;
+    const length = arguments.length;
+    if (!length) {
+      return "";
+    }
+    let result = "";
+    while (++index < length) {
+      let codePoint = Number(arguments[index]);
+      if (
+        !isFinite(codePoint) || // `NaN`, `+Infinity`, or `-Infinity`
+        codePoint < 0 || // not a valid Unicode code point
+        codePoint > 0x10FFFF || // not a valid Unicode code point
+        floor(codePoint) != codePoint // not an integer
+      ) {
+        throw RangeError("Invalid code point: " + codePoint);
+      }
+      if (codePoint <= 0xFFFF) { // BMP code point
+        codeUnits.push(codePoint);
+      } else { // Astral code point; split in surrogate halves
+        // https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
+        codePoint -= 0x10000;
+        highSurrogate = (codePoint >> 10) + 0xD800;
+        lowSurrogate = (codePoint % 0x400) + 0xDC00;
+        codeUnits.push(highSurrogate, lowSurrogate);
+      }
+      if (index + 1 == length || codeUnits.length > MAX_SIZE) {
+        result += stringFromCharCode.apply(null, codeUnits);
+        codeUnits.length = 0;
+      }
+    }
+    return result;
+  };
+}
+
+export default fromCodePoint;

src/plugins/jsx/index.js

@@ -1,5 +1,7 @@
 /* eslint indent: 0 */
 
+import fromCodePoint from "./fromCodePoint";
+
 import XHTMLEntities from "./xhtml";
 import { TokenType, types as tt } from "../../tokenizer/types";
 import { TokContext, types as tc } from "../../tokenizer/context";
@@ -136,11 +138,11 @@ pp.jsxReadEntity = function() {
         if (str[1] === "x") {
           str = str.substr(2);
           if (HEX_NUMBER.test(str))
-            entity = String.fromCharCode(parseInt(str, 16));
+            entity = fromCodePoint(parseInt(str, 16));
         } else {
           str = str.substr(1);
           if (DECIMAL_NUMBER.test(str))
-            entity = String.fromCharCode(parseInt(str, 10));
+            entity = fromCodePoint(parseInt(str, 10));
         }
       } else {
         entity = XHTMLEntities[str];

test/fixtures/jsx/basic/entity/expected.json

@@ -136,7 +136,7 @@
                 }
               },
               "extra": null,
-              "value": ""
+              "value": "💩"
             }
           ]
         }