Confirm the answer according to #5

README.md

@@ -12,7 +12,7 @@ This proposal is currently [stage 1](https://github.com/tc39/proposals/blob/mast
 Let us consider a few scenarios from the real world to understand what we are trying to solve in this proposal.
 
 * On `MouseEvent` we are interested on `'ctrlKey', 'shiftKey', 'altKey', 'metaKey'` events only.
-* We have a `configObject` and we need `['dependencies', 'devDependencies', 'peerDependencies']` from it. 
+* We have a `configObject` and we need `['dependencies', 'devDependencies', 'peerDependencies']` from it.
 * We have an `optionsBag`and we would allow on `['shell', 'env', 'extendEnv', 'uid', 'gid']` on it.
 * From a `req.body` we want to extract `['name', 'company', 'email', 'password']`
 * Checking if a component `shouldReload` by extracting `compareKeys` from `props` and compare it with `prevProps`.
@@ -77,7 +77,7 @@ Object.omit(obj[, omittedKeys | predictedFunction(currentValue[, key[, object]])
 - `obj`: which object you want to pick or omit.
 - `pickedKeys` (**optional**): keys of properties you want to pick from the object. The default value is an empty array.
 - `omittedKeys` (**optional**): keys of properties you want to pick from the object. The default value is an empty array.
-- `predictedFunction` (**optional**): the function to predicted whether the property should be picked or omitted. The default value is an identity: `x => x`.
+- `predictedFunction` (**optional**): the function to predict whether the property should be picked or omitted. The default value is an identity: `x => x`.
   - `currentValue`: the current value processed in the object.
   - `key`: the key of the `currentValue` in the object.
   - `object`: the object `pick` was called upon.
@@ -104,7 +104,7 @@ Object.omit({a : 1, b : 2}, ['b']); // => {a: 1}
 Object.pick({a : 1, b : 2}, ['c']); // => {}
 Object.omit({a : 1, b : 2}, ['c']); // => {a: 1, b: 2}
 
-Object.pick([], [Symbol.iterator]); // => {Symbol(Symbol.iterator): f}
+Object.pick([], [Symbol.iterator]); // => {Symbol(Symbol.iterator): Array.prototype[Symbol.iterator]}
 Object.pick([], ['length']); // => {length: 0}
 
 Object.pick({a : 1, b : 2}, v => v === 1); // => {a: 1}
@@ -124,54 +124,67 @@ Object.pick({a : 1, b : 2}, (v, k) => k !== 'b'); // => {a: 1}
     - square brackets:
 
         ```js
-        ({a : 1, b : 2, c : 3}).['a', 'b']; // => {a : 1, b : 2}
+        ({a : 1, b : 2, c : 3}).['a', 'b']; // => {a: 1, b: 2}
 
         const keys = ['a', 'b'];
-        ({a : 1, b : 2, c : 3}).[keys[0], keys[1]]; // => {a : 1, b : 2}
-        ({a : 1, b : 2, c : 3}).[...keys]; // => {a : 1, b : 2}
+        ({a : 1, b : 2, c : 3}).[keys[0], keys[1]]; // => {a: 1, b: 2}
+        ({a : 1, b : 2, c : 3}).[...keys]; // => {a: 1, b: 2}
         ```
 
     - curly brackets
 
         ```js
-        ({a : 1, b : 2, c : 3}).{a, b} // => {a : 1, b : 2}
+        ({a : 1, b : 2, c : 3}).{a, b} // => {a: 1, b: 2}
 
         const keys = ['a', 'b'];
-        ({a : 1, b : 2, c : 3}).{[keys[0]], b}; // => {a : 1}
-        ({a : 1, b : 2, c : 3}).{[...keys]}; // => {a : 1, b : 2}
+        ({a : 1, b : 2, c : 3}).{[keys[0]], b}; // => {a: 1}
+        ({a : 1, b : 2, c : 3}).{[...keys]}; // => {a: 1, b: 2}
 
         // Similar to destructuring
-        ({a : 1, b : 2, c : 3}).{a, b : B}; // => {a : 1, B : 2}
+        ({a : 1, b : 2, c : 3}).{a, b : B}; // => {a: 1, B: 2}
         ```
 
-        Currently, there is a disagreement on whether properties with default assignment values should be picked.
+        ~~Currently, there is a disagreement on whether properties with default assignment values should be picked.~~ It has been reviewed in [#6](https://github.com/tc39-transfer/proposal-object-pick-or-omit/pull/6) which confirmed that the `.{...}` statement should denote what the new object should contain like restructuring:
 
         ```js
-        // If considering the meaning of picking, the initial value has no meanings
-        ({a : 1, b : 2, c : 3}).{a, d = 2}; // => {a : 1}
-
-        // If considering as "restructuring", the shortcut has its reason to pick
-        ({a : 1, b : 2, c : 3}).{a, d = 2}; // => {a : 1, d : 2}
+        ({a : 1, b : 2, c : 3}).{a, d = 2}; // => {a: 1, d: 2}
+        ({a : 1, b : 2, c : 3, d : 4}).{a, d = 2}; // => {a: 1, d: 4} 
         ```
 
-    Nevertheless, it is just a simple vision, and feel free to discuss.
+    Nevertheless, it is just a simple vision, and feel free to discuss it.
 
 ### FAQ
 
-1. When it comes to the prototype chain of an object, should the method pick or omit it? (The answer may change)
+1. When it comes to the prototype chain of an object, should the method pick or omit it?
 
-    A: The implementation of [`_.pick`](https://lodash.com/docs/4.17.15#pick) and [`_.omit`](https://lodash.com/docs/4.17.15#omit) by Lodash has taken care about the chain. To keep the rule, we can pick off properties of prototype, but can't omit them:
+    A: Consistent with destructuring: we can explicitly pick off properties of the prototype, but we can't modify them by calling `Object.omit`.
 
     ```js
-    Object.pick({a : 1}, ['toString']); // => {toString: f}
-    Object.omit({a : 1}, ['toString']).toString; // => ƒ toString() { [native code] }
+    Object.pick([1, 2, 3], ['length']); // => {length: 3}
+    // equivalent to the behavior
+    const {length} = [1, 2, 3];
+    length; // => 3
+
+    // cannot omit the prototype of an array by calling `Object.omit`
+    const arr = [1, 2, 3];
+    Object.omit(arr, ['length']);
+    arr.length; // => 3
     ```
 
-    The same rule applies to `__proto__` event if it has been [deprecated](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto), because the proposal should be pure enough to not specify a special logic to eliminate deprecated properties:
+    The implementation of [`_.pick`](https://lodash.com/docs/4.17.15#pick) and [`_.omit`](https://lodash.com/docs/4.17.15#omit) by Lodash has also taken care about the chain.
+
+    The same rule applies to `__proto__` event if it has been [deprecated](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto) because the proposal should be pure enough to not specify a special logic to eliminate deprecated properties:
 
     ```js
-    Object.pick({}, ['__proto__']); // => {__proto__: {...}}
-    Object.omit({}, ['__proto__']).__proto__; // => {...} 
+    Object.pick({}, ['__proto__']); // => {__proto__: Object.prototype}
+    // equivalent to the behavior
+    const {__proto__} = {};
+    __proto__; // => Object.prototype
+
+    Object.omit({}, ['__proto__']).__proto__; // => Object.prototype
+    // equivalent to the behavior
+    const {__proto__, ...res} = {}
+    res.__proto__; // => Object.prototype
     ```
 
     In some opinions, picking off or omitting properties from the prototype chain should make the method more extendable:
@@ -181,41 +194,70 @@ Object.pick({a : 1, b : 2}, (v, k) => k !== 'b'); // => {a: 1}
     const omitOwn = (obj, keys) => Object.omit(obj, keys.filter(key => obj.hasOwnProperty(key)));
     ```
 
-2. What is the type of the returned value?
+2. What is the type of returned value?
 
-    A: All these methods should return plain objects:
+    A: Consistent with destructuring: should return plain objects.
 
     ```js
-    Object.pick([]); // => {} 
+    Object.pick([]); // => {}
     Object.omit([]); // => {}
-    Object.pick(new Map()); // => {} 
+    Object.pick(new Map()); // => {}
     Object.omit(new Map()); // => {}
+
+    // equivalent to the behavior
+    const {...res} = [];
+    res instanceof Array; // => false
+    const {...res} = new Map();
+    res instanceof Map; // => false
+    const {...res} = new Set();
+    res instanceof Set; // => false
     ```
 
 3. How to handle `Symbol`?
 
-    A: `Symbol` should just be considered as properties within `Symbol` keys, and they should obey the rules mentioned above:
+    A: Consistent with destructuring.
 
     ```js
-    Object.pick([], [Symbol.iterator]); // => {Symbol(Symbol.iterator): f}, pick off from the prototype
+    Object.pick([], [Symbol.iterator]); // => {Symbol(Symbol.iterator): Array.prototype[Symbol.iterator]}, pick off from the prototype
+    // equivalent to the behavior
+    const {[Symbol.iterator] : iter} = [];
+    iter; // => Array.prototype[Symbol.iterator]
+
     Object.omit([], [Symbol.iterator]); // => {}, plain objects
+    // equivalent to the behavior
+    const {[Symbol.iterator] : iter, ...res} = [];
+    res instanceof Array; // => false
 
     const symbol = Symbol('key');
-    Object.omit({a : 1, [symbol]: 2}, [symbol]); // => {a : 1}
+    Object.omit({a : 1, [symbol]: 2}, [symbol]); // => {a: 1}
+    // equivalent to the behavior
+    const {[symbol] : _, ...res} = {a : 1, [symbol]: 2};
+    res; // => {a : 1}
 
     Object.prototype[symbol] = 'test'; // override prototype
     Object.pick({}, [symbol]); // => {Symbol(key): "test"}, pick off from the prototype
     Object.omit({}, [symbol])[symbol]; // => "test", cannot omit properties from the prototype
+    // equivalent to the behavior
+    const {[symbol] : sym, ...res} = {};
+    sym; // => 'test'
+    res[symbol]; // => 'test'
     ```
 
 4. If some properties of an object are not accessible like throwing an error, can `Object.pick` or `Object.omit` operate such an object?
 
-    A: I suggest throwing the error wrapped by `Object.pick` or `Object.omit`, but it is **NOT the final choice**:
+    A: Consistent with destructuring: throw the error wrapped by `Object.pick` or `Object.omit`.
 
     ```js
     Object.pick(Object.defineProperty({}, 'key', {
-       get() { throw new Error() }
+       get() { throw new Error(); }
     }), ['key']);
+    // equivalent to the behavior
+    const o = Object.defineProperty({}, 'key', {
+      get() { throw new Error('custom'); }
+    });
+    try { const {key} = o; } catch (e) {
+       e.message // => 'custom'
+    }
     ```
 
     The error stack will look like this:
@@ -224,7 +266,7 @@ Object.pick({a : 1, b : 2}, (v, k) => k !== 'b'); // => {a: 1}
     Uncaught Error
         at Object.get (<anonymous>:2:20)
         at Object.pick (<anonymous>:2:10)
-        at <anonymous>:1:8 
+        at <anonymous>:1:8
     ```
 
 5. In comparison with [**proposal-shorthand-improvements**](https://github.com/rbuckton/proposal-shorthand-improvements), when should we use these two methods?
@@ -233,16 +275,16 @@ Object.pick({a : 1, b : 2}, (v, k) => k !== 'b'); // => {a: 1}
 
     ```js
     postData({[key1] : o[key1], [key2] : o[key2]});
-    postData(Object.pick(o, [key1, key2])); 
+    postData(Object.pick(o, [key1, key2]));
     ```
 
 6. Why can't be defined on the `Object.prototype` directly?
 
-    A: As `Object` is especially fundamental, and both of them will result in conflicts of properties of any other objects. In shorthand, if defined, any objects inherited from `Object` with `pick` or `omit` defined in its prototype should break.
+    A: As `Object` is especially fundamental, both of them will result in conflicts of properties of any other objects. In shorthand, if defined, any objects inherited from `Object` with `pick` or `omit` defined in its prototype would break. Also, objects that inherit from `null` would be left unable to use this functionality.
 
 7. Why not define filtered methods corresponding to two actions: [`pickBy`](https://lodash.com/docs/4.17.15#pickBy) and [`omitBy`](https://lodash.com/docs/4.17.15#omitBy) like Lodash?
 
-    A: It is [unnecessary](https://github.com/aleen42/proposal-object-pick-or-omit/issues/2) to double two methods, because it can be combined into the argument instead:
+    A: It is [unnecessary](https://github.com/aleen42/proposal-object-pick-or-omit/issues/2) to double two methods because they can be combined into the argument instead:
 
     Besides, the passing filtered method can be easily reversed with equal meaning, and it means that `omitBy` can be easily defined as `pickBy`'s inverse.