Keep object key with escape sequence as it is (#8160)

changelog_unreleased/javascript/pr-8160.md

@@ -0,0 +1,20 @@
+#### Keep object key with escape sequence as it is ([#8160](https://github.com/prettier/prettier/pull/8160) by [@fisker](https://github.com/fisker))
+
+<!-- prettier-ignore -->
+```js
+// Input
+const a = {
+  "\u2139": 'why "\\u2139" converted to "i"?',
+};
+
+// Prettier stable
+const a = {
+  ℹ: 'why "\\u2139" converted to "i"?',
+};
+
+
+// Prettier master
+const a = {
+  "\u2139": 'why "\\u2139" is converted to "i"?',
+};
+```

src/language-js/utils.js

@@ -729,6 +729,7 @@ function isStringPropSafeToCoerceToIdentifier(node, options) {
   return (
     isStringLiteral(node.key) &&
     isIdentifierName(node.key.value) &&
+    rawText(node.key).slice(1, -1) === node.key.value &&
     options.parser !== "json" &&
     // With `--strictPropertyInitialization`, TS treats properties with quoted names differently than unquoted ones.
     // See https://github.com/microsoft/TypeScript/pull/20075

tests/objects/__snapshots__/jsfmt.spec.js.snap

@@ -1,5 +1,33 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`escape sequence-key.js format 1`] = `
+====================================options=====================================
+parsers: ["babel"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+// #6235
+const a = {
+  '\\u2139': 'why "\\\\u2139" is converted to "i"?',
+};
+
+const a = {
+  "\\x66\\x69\\x73\\x6b\\x65\\x72": "\\x66\\x69\\x73\\x6b\\x65\\x72",
+};
+
+=====================================output=====================================
+// #6235
+const a = {
+  "\\u2139": 'why "\\\\u2139" is converted to "i"?',
+};
+
+const a = {
+  "\\x66\\x69\\x73\\x6b\\x65\\x72": "\\x66\\x69\\x73\\x6b\\x65\\x72",
+};
+
+================================================================================
+`;
+
 exports[`expand.js format 1`] = `
 ====================================options=====================================
 parsers: ["babel"]

tests/objects/escape sequence-key.js

@@ -0,0 +1,8 @@
+// #6235
+const a = {
+  '\u2139': 'why "\\u2139" is converted to "i"?',
+};
+
+const a = {
+  "\x66\x69\x73\x6b\x65\x72": "\x66\x69\x73\x6b\x65\x72",
+};