[eslint config] [*] [new] set ecmaVersion to 2017; enable object rest/spread; update babel-preset-airbnb

README.md

@@ -293,6 +293,26 @@ Other Style Guides
   console.log(has.call(object, key));
   ```
 
+  <a name="objects--rest-spread"></a>
+  - [3.10](#objects--rest-spread) Prefer the object spread operator over `Object.assign` to shallow-copy objects. Use the object rest operator to get a new object with certain properties omitted.
+
+  ```javascript
+  // very bad
+  const original = { a: 1, b: 2 };
+  const copy = Object.assign(original, { c: 3 }); // this mutates `original` ಠ_ಠ
+  delete copy.a; // so does this
+
+  // bad
+  const original = { a: 1, b: 2 };
+  const copy = Object.assign({}, original, { c: 3 }); // copy => { a: 1, b: 2, c: 3 }
+
+  // good
+  const original = { a: 1, b: 2 };
+  const copy = { ...original, c: 3 }; // copy => { a: 1, b: 2, c: 3 }
+
+  const { a, ...noA } = copy; // noA => { b: 2, c: 3 }
+  ```
+
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 ## Arrays