diff --git a/1-js/05-data-types/02-number/article.md b/1-js/05-data-types/02-number/article.md
index a1056bd969..becdd2e6ea 100644
--- a/1-js/05-data-types/02-number/article.md
+++ b/1-js/05-data-types/02-number/article.md
@@ -148,7 +148,7 @@ alert( num.toString(2) );   // 11111111
 
 1. 乘除法
 
-    例如，要将数字舍入到小数点后两位，我们可以将数字乘以 `100`，调用舍入函数，然后再将其除回。
+    例如，要将数字舍入到小数点后两位，我们可以将数字乘以 `100`（或更大的 10 的整数次幂），调用舍入函数，然后再将其除回。
     ```js run
     let num = 1.23456;
 
diff --git a/1-js/05-data-types/10-destructuring-assignment/article.md b/1-js/05-data-types/10-destructuring-assignment/article.md
index d68856264a..73c183171c 100644
--- a/1-js/05-data-types/10-destructuring-assignment/article.md
+++ b/1-js/05-data-types/10-destructuring-assignment/article.md
@@ -121,6 +121,25 @@ for (let [key, value] of user) {
 }
 ```
 ````
+
+```smart header="Swap variables trick"
+A well-known trick for swapping values of two variables:
+
+```js run
+let guest = "Jane";
+let admin = "Pete";
+
+// Swap values: make guest=Pete, admin=Jane
+[guest, admin] = [admin, guest];
+
+alert(`${guest} ${admin}`); // Pete Jane (successfully swapped!)
+```
+
+Here we create a temporary array of two variables and immediately destructure it in swapped order.
+
+We can swap more than two variables this way.
+
+
 ### 剩余的 '...'
 
 如果我们不只是要获得第一个值，还要将后续的所有元素都收集起来 — 我们可以使用三个点 `"..."` 来再加一个参数来接收“剩余的”元素：
diff --git a/1-js/05-data-types/11-date/6-get-seconds-today/solution.md b/1-js/05-data-types/11-date/6-get-seconds-today/solution.md
index 58fec592b4..f830c7d12b 100644
--- a/1-js/05-data-types/11-date/6-get-seconds-today/solution.md
+++ b/1-js/05-data-types/11-date/6-get-seconds-today/solution.md
@@ -23,4 +23,6 @@ function getSecondsToday() {
   let d = new Date();
   return d.getHours() * 3600 + d.getMinutes() * 60 + d.getSeconds();
 };
+
+alert( getSecondsToday() );
 ```
diff --git a/1-js/06-advanced-functions/02-rest-parameters-spread/article.md b/1-js/06-advanced-functions/02-rest-parameters-spread/article.md
index 31c4b14852..f09e3f5927 100644
--- a/1-js/06-advanced-functions/02-rest-parameters-spread/article.md
+++ b/1-js/06-advanced-functions/02-rest-parameters-spread/article.md
@@ -225,11 +225,11 @@ alert( Array.from(str) ); // H,e,l,l,o
 因此，对于将一些“东西”转换为数组的任务，`Array.from` 往往更通用。
 
 
-## 获取一个 object/array 的副本
+## 获取一个 array/object 的副本
 
-还记得我们 [之前讲过的](https://zh.javascript.info/object#fu-zhi-he-he-bing-objectassign) `Object.assign()` 吗？
+还记得我们 [之前讲过的](info:object-copy#fu-zhi-he-he-bing-objectassign) `Object.assign()` 吗？
 
-使用 spread 操作符也可以做同样的事情。
+使用 spread 语法也可以做同样的事情。
 
 ```js run
 let arr = [1, 2, 3];
diff --git a/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/solution.js b/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/solution.js
new file mode 100644
index 0000000000..8a71c869d9
--- /dev/null
+++ b/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/solution.js
@@ -0,0 +1,3 @@
+function byField(fieldName){
+  return (a, b) => a[fieldName] > b[fieldName] ? 1 : -1;
+}
diff --git a/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/source.js b/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/source.js
new file mode 100644
index 0000000000..23b4338340
--- /dev/null
+++ b/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/source.js
@@ -0,0 +1,5 @@
+function byField(fieldName){
+
+  // Your code goes here.
+
+}
diff --git a/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/test.js b/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/test.js
new file mode 100644
index 0000000000..e3c335e03a
--- /dev/null
+++ b/1-js/06-advanced-functions/03-closure/9-sort-by-field/_js.view/test.js
@@ -0,0 +1,39 @@
+describe("byField", function(){
+
+  let users = [
+    { name: "John", age: 20, surname: "Johnson" },
+    { name: "Pete", age: 18, surname: "Peterson" },
+    { name: "Ann", age: 19, surname: "Hathaway" },
+  ];
+
+  it("sorts users by name", function(){
+    let nameSortedKey = [
+      { name: "Ann", age: 19, surname: "Hathaway" },
+      { name: "John", age: 20, surname: "Johnson"},
+      { name: "Pete", age: 18, surname: "Peterson" },
+    ];
+    let nameSortedAnswer = users.sort(byField("name"));
+    assert.deepEqual(nameSortedKey, nameSortedAnswer);
+  });
+
+  it("sorts users by age", function(){
+    let ageSortedKey = [
+      { name: "Pete", age: 18, surname: "Peterson" },
+      { name: "Ann", age: 19, surname: "Hathaway" },
+      { name: "John", age: 20, surname: "Johnson"},
+    ];
+    let ageSortedAnswer = users.sort(byField("age"));
+    assert.deepEqual(ageSortedKey, ageSortedKey);
+  });
+
+  it("sorts users by surname", function(){
+    let surnameSortedKey = [
+      { name: "Ann", age: 19, surname: "Hathaway" },
+      { name: "John", age: 20, surname: "Johnson"},
+      { name: "Pete", age: 18, surname: "Peterson" },
+    ];
+    let surnameSortedAnswer = users.sort(byField("surname"));
+    assert.deepEqual(surnameSortedAnswer, surnameSortedKey);
+  });
+
+});
diff --git a/1-js/06-advanced-functions/03-closure/9-sort-by-field/solution.md b/1-js/06-advanced-functions/03-closure/9-sort-by-field/solution.md
index bd57085eaf..8b13789179 100644
--- a/1-js/06-advanced-functions/03-closure/9-sort-by-field/solution.md
+++ b/1-js/06-advanced-functions/03-closure/9-sort-by-field/solution.md
@@ -1,22 +1 @@
 
-
-```js run
-let users = [
-  { name: "John", age: 20, surname: "Johnson" }, 
-  { name: "Pete", age: 18, surname: "Peterson" },
-  { name: "Ann", age: 19, surname: "Hathaway" }
-];
-
-*!*
-function byField(field) {
-  return (a, b) => a[field] > b[field] ? 1 : -1;
-}
-*/!*
-
-users.sort(byField('name'));
-users.forEach(user => alert(user.name)); // Ann, John, Pete
-
-users.sort(byField('age'));
-users.forEach(user => alert(user.name)); // Pete, Ann, John
-```
-
diff --git a/1-js/06-advanced-functions/04-var/article.md b/1-js/06-advanced-functions/04-var/article.md
index 0be262b98a..bdc96ef265 100644
--- a/1-js/06-advanced-functions/04-var/article.md
+++ b/1-js/06-advanced-functions/04-var/article.md
@@ -13,27 +13,18 @@
 2. `const`
 3. `var`
 
-`let` 和 `const` 在词法环境中的行为完全一样。
-
-但 `var` 却是一头完全不同的，源自非常古老的时代的怪兽。在现代脚本中一般不再使用它，但它仍然潜伏在旧脚本中。
-
-如果你不打算接触这样的脚本，你甚至可以跳过本章或推迟阅读本章，但是之后你很可能会踩到它的坑。
-
-乍一看，`var` 和 `let` 的行为相似，不就是声明变量嘛：
+The `var` declaration is similar to `let`. Most of the time we can replace `let` by `var` or vice-versa and expect things to work:
 
 ```js run
-function sayHi() {
-  var phrase = "Hello"; // 局部变量，使用 "var"，而不是 "let"
-
-  alert(phrase); // Hello
-}
+var message = "Hi";
+alert(message); // Hi
+```
 
-sayHi();
+But internally `var` is a very different beast, that originates from very old times. It's generally not used in modern scripts, but still lurks in the old ones.
 
-alert(phrase); // Error, phrase is not defined
-```
+If you don't plan on meeting such scripts you may even skip this chapter or postpone it.
 
-……但两者存在区别。
+On the other hand, it's important to understand differences when migrating old scripts from `var` to `let`, to avoid odd errors.
 
 ## "var" 没有块级作用域
 
@@ -94,7 +85,27 @@ alert(phrase); // Error: phrase is not defined (Check the Developer Console)
 
 可以看到，`var` 穿透了 `if`，`for` 和其它代码块。这是因为在早期的 JavaScript 中，块没有词法环境。而 `var` 就是这个时期的代表之一。
 
-## "var" 声明在函数开头就会被处理
+## "var" 允许重新声明
+
+If we declare the same variable with `let` twice in the same scope, that's an error:
+
+```js run
+let user;
+let user; // SyntaxError: 'user' has already been declared
+```
+
+With `var`, we can redeclare a variable any number of times. If we use `var` with an already-declared variable, it's just ignored:
+
+```js run
+var user = "Pete";
+
+var user = "John"; // this "var" does nothing (already declared)
+// ...it doesn't trigger an error
+
+alert(user); // John
+```
+
+## "var" variables can be declared below their use
 
 当函数开始的时候，就会处理 `var` 声明（脚本启动对应全局变量）。
 
diff --git a/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/solution.js b/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/solution.js
new file mode 100644
index 0000000000..c7d7d734ea
--- /dev/null
+++ b/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/solution.js
@@ -0,0 +1,15 @@
+function sum(a) {
+
+  let currentSum = a;
+
+  function f(b) {
+    currentSum += b;
+    return f;
+  }
+
+  f.toString = function() {
+    return currentSum;
+  };
+
+  return f;
+}
diff --git a/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/source.js b/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/source.js
new file mode 100644
index 0000000000..f10dca5dc8
--- /dev/null
+++ b/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/source.js
@@ -0,0 +1,12 @@
+function sum(a){
+  // Your code goes here.
+
+}
+
+/*
+sum(1)(2) == 3; // 1 + 2
+sum(1)(2)(3) == 6; // 1 + 2 + 3
+sum(5)(-1)(2) == 6
+sum(6)(-1)(-2)(-3) == 0
+sum(0)(1)(2)(3)(4)(5) == 15
+*/
diff --git a/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/test.js b/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/test.js
new file mode 100644
index 0000000000..ed567d3306
--- /dev/null
+++ b/1-js/06-advanced-functions/06-function-object/5-sum-many-brackets/_js.view/test.js
@@ -0,0 +1,19 @@
+describe("sum", function(){
+  
+  it("sum(1)(2) == 3", function(){
+    assert.equal(3, sum(1)(2));
+  });
+
+  it("sum(5)(-1)(2) == 6", function(){
+    assert.equal(6, sum(5)(-1)(2));
+  });
+  
+  it("sum(6)(-1)(-2)(-3) == 0", function(){
+    assert.equal(0, sum(6)(-1)(-2)(-3));
+  });
+
+  it("sum(0)(1)(2)(3)(4)(5) == 15", function(){
+    assert.equal(15, sum(0)(1)(2)(3)(4)(5));
+  });
+});
+
diff --git a/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/_js.view/test.js b/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/_js.view/test.js
index d2cf8e1519..e671438f6f 100644
--- a/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/_js.view/test.js
+++ b/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/_js.view/test.js
@@ -7,8 +7,8 @@ describe("throttle(f, 1000)", function() {
   }
 
   before(function() {
-    f1000 = throttle(f, 1000);
     this.clock = sinon.useFakeTimers();
+    f1000 = throttle(f, 1000);
   });
 
   it("the first call runs now", function() {
diff --git a/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/task.md b/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/task.md
index ba1e5b61fd..0e2ae4001b 100644
--- a/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/task.md
+++ b/1-js/06-advanced-functions/09-call-apply-decorators/04-throttle/task.md
@@ -4,9 +4,13 @@ importance: 5
 
 # 节流装饰者
 
-创建一个“节流”装饰者 `throttle(f, ms)` —— 返回一个包装器，最多每隔 `1ms` 将调用传递给 `f` 一次。那些属于“冷却”期的调用将被忽略。
+创建一个“节流”装饰者 `throttle(f, ms)` —— 返回一个包装器。
 
-**与 `debounce` 的区别 —— 如果被忽略的调用是冷却期间的最后一次，那么它会在延时结束时执行。**
+When it's called multiple times, it passes the call to `f` at maximum once per `ms` milliseconds.
+
+The difference with debounce is that it's completely different decorator:
+- `debounce` runs the function once after the "cooldown" period. Good for processing the final result.
+- `throttle` runs it not more often than given `ms` time. Good for regular updates that shouldn't be very often.
 
 让我们看看现实生活中的应用程序，以便更好地理解这个需求，并了解它的来源。
 
@@ -14,7 +18,7 @@ importance: 5
 
 在浏览器中，我们可以设置一个函数，使其在每次鼠标移动时运行，并获取鼠标移动时的指针位置。在使用鼠标的过程中，此函数通常会执行地非常频繁，大概每秒 100 次（每 10 毫秒）。
 
-**当鼠标指针移动时，我们想要更新网页上的某些信息。**
+**我们想要在鼠标指针移动时，更新网页上的某些信息。**
 
 ……但是更新函数 `update()` 太重了，无法在每个微小移动上都执行。高于每 100ms 更新一次的更新频次也没有意义。
 
diff --git a/1-js/06-advanced-functions/09-call-apply-decorators/article.md b/1-js/06-advanced-functions/09-call-apply-decorators/article.md
index 8388f82259..662dda98a5 100644
--- a/1-js/06-advanced-functions/09-call-apply-decorators/article.md
+++ b/1-js/06-advanced-functions/09-call-apply-decorators/article.md
@@ -209,7 +209,7 @@ alert( worker.slow(2) ); // 工作正常，没有调用原始函数（使用的
 2. 因此，当 `worker.slow(2)` 执行时，包装器将 `2` 作为参数，并且 `this=worker`（它是点符号 `.` 之前的对象）。
 3. 在包装器内部，假设结果尚未缓存，`func.call(this, x)` 将当前的 `this`（`=worker`）和当前的参数（`=2`）传递给原始方法。
 
-## 使用 "func.apply" 来传递多参数
+## 传递多个参数
 
 现在让我们把 `cachingDecorator` 写得更加通用。到现在为止，它只能用于单参数函数。
 
@@ -236,7 +236,7 @@ worker.slow = cachingDecorator(worker.slow);
 
 对于许多实际应用，第三种方式就足够了，所以我们就用这个吧。
 
-当然，我们需要将 `func.call(this, x)` 替换成 `func.call(this, ...arguments)`，以将所有参数传递给包装的函数调用，而不仅仅是只传递第一个参数。
+Also we need to pass not just `x`, but all arguments in `func.call`. Let's recall that in a `function()` we can get a pseudo-array of its arguments as `arguments`, so `func.call(this, x)` should be replaced with `func.call(this, ...arguments)`.
 
 这是一个更强大的 `cachingDecorator`：
 
@@ -284,6 +284,8 @@ alert( "Again " + worker.slow(3, 5) ); // same (cached)
 - 在 `(*)` 行中它调用 `hash` 来从 `arguments` 创建一个单独的键。这里我们使用一个简单的“连接”函数，将参数 `(3, 5)` 转换为键 `"3,5"`。更复杂的情况可能需要其他哈希函数。
 - 然后 `(**)` 行使用 `func.call(this, ...arguments)` 将包装器获得的上下文和所有参数（不仅仅是第一个参数）传递给原始函数。
 
+## func.apply
+
 我们可以使用 `func.apply(this, arguments)` 代替 `func.call(this, ...arguments)`。
 
 内建方法 [func.apply](mdn:js/Function/apply) 的语法是：
@@ -308,9 +310,9 @@ func.apply(context, args);   // 与使用 call 相同
 - Spread 语法 `...` 允许将 **可迭代对象** `args` 作为列表传递给 `call`。
 - `apply` 仅接受 **类数组对象** `args`。
 
-因此，这些调用可以相互补充。当我们期望可迭代对象时，使用 `call`，当我们期望类数组对象时，使用 `apply`。
+因此，当我们期望可迭代对象时，使用 `call`，当我们期望类数组对象时，使用 `apply`。
 
-对于即可迭代又是类数组的对象，例如一个真正的数组，从技术上讲我们使用 `call` 或 `apply` 都行，但是 `apply` 可能会更快，因为大多数 JavaScript 引擎在内部对其进行了优化。
+对于即可迭代又是类数组的对象，例如一个真正的数组，我们使用 `call` 或 `apply` 均可，但是 `apply` 可能会更快，因为大多数 JavaScript 引擎在内部对其进行了优化。
 
 将所有参数连同上下文一起传递给另一个函数被称为“呼叫转移（call forwarding）”。
 
diff --git a/1-js/07-object-properties/02-property-accessors/article.md b/1-js/07-object-properties/02-property-accessors/article.md
index 79f74fac66..7a9b450af8 100644
--- a/1-js/07-object-properties/02-property-accessors/article.md
+++ b/1-js/07-object-properties/02-property-accessors/article.md
@@ -1,7 +1,7 @@
 
 # 属性的 getter 和 setter
 
-有两种类型的属性。
+有两种类型的对象属性。
 
 第一种是 **数据属性**。我们已经知道如何使用它们了。到目前为止，我们使用过的所有属性都是数据属性。
 
diff --git a/1-js/08-prototypes/04-prototype-methods/article.md b/1-js/08-prototypes/04-prototype-methods/article.md
index b21172ee97..0193abebd7 100644
--- a/1-js/08-prototypes/04-prototype-methods/article.md
+++ b/1-js/08-prototypes/04-prototype-methods/article.md
@@ -57,7 +57,6 @@ alert(rabbit.jumps); // true
 我们可以使用 `Object.create` 来实现比复制 `for..in` 循环中的属性更强大的对象克隆方式：
 
 ```js
-// 完全相同的对象 obj 的浅拷贝
 let clone = Object.create(Object.getPrototypeOf(obj), Object.getOwnPropertyDescriptors(obj));
 ```
 
@@ -116,7 +115,7 @@ alert(obj[key]); // [object Object]，并不是 "some value"！
 
 我们怎么避免这样的问题呢？
 
-首先，我们可以改用 `Map`，那么一切都迎刃而解。
+首先，我们可以改用 `Map` 来代替普通对象进行存储，这样一切都迎刃而解。
 
 但是 `Object` 在这里同样可以运行得很好，因为 JavaScript 语言的制造者很早就注意到了这个问题。
 
@@ -128,7 +127,7 @@ alert(obj[key]); // [object Object]，并不是 "some value"！
 
 就像在本部分教程的开头所说的那样：`__proto__` 是一种访问 `[[Prototype]]` 的方式，而不是 `[[prototype]]` 本身。
 
-现在，我们想要将一个对象用作关联数组，我们可以使用一些小技巧：
+现在，我们想要将一个对象用作关联数组，并且摆脱此类问题，我们可以使用一些小技巧：
 
 ```js run
 *!*