planning

node_modules/micromark-util-decode-numeric-character-reference/index.js

@@ -0,0 +1,36 @@
+/**
+ * Turn the number (in string form as either hexa- or plain decimal) coming from
+ * a numeric character reference into a character.
+ *
+ * Sort of like `String.fromCharCode(Number.parseInt(value, base))`, but makes
+ * non-characters and control characters safe.
+ *
+ * @param {string} value
+ *   Value to decode.
+ * @param {number} base
+ *   Numeric base.
+ * @returns {string}
+ *   Character.
+ */
+export function decodeNumericCharacterReference(value, base) {
+  const code = Number.parseInt(value, base)
+  if (
+    // C0 except for HT, LF, FF, CR, space.
+    code < 9 ||
+    code === 11 ||
+    (code > 13 && code < 32) ||
+    // Control character (DEL) of C0, and C1 controls.
+    (code > 126 && code < 160) ||
+    // Lone high surrogates and low surrogates.
+    (code > 55295 && code < 57344) ||
+    // Noncharacters.
+    (code > 64975 && code < 65008) /* eslint-disable no-bitwise */ ||
+    (code & 65535) === 65535 ||
+    (code & 65535) === 65534 /* eslint-enable no-bitwise */ ||
+    // Out of range
+    code > 1114111
+  ) {
+    return '\uFFFD'
+  }
+  return String.fromCharCode(code)
+}