Merge branch 'master' of github.com:javascript-tutorial/en.javascript.info into sync-b52aa942

Author: iliakan

1-js/02-first-steps/08-operators/3-primitive-conversions-questions/solution.md

@@ -10,8 +10,8 @@ true + false = 1
 "4" - 2 = 2
 "4px" - 2 = NaN
 7 / 0 = Infinity
-" -9  " + 5 = " -9  5" // (3)
-" -9  " - 5 = -14 // (4)
+"  -9  " + 5 = "  -9  5" // (3)
+"  -9  " - 5 = -14 // (4)
 null + 1 = 1 // (5)
 undefined + 1 = NaN // (6)
 " \t \n" - 2 = -2 // (7)

1-js/02-first-steps/12-nullish-coalescing-operator/article.md

@@ -60,11 +60,11 @@ alert(height || 100); // 100
 alert(height ?? 100); // 0
 ```
 
-Here, `height || 100` treats zero height as unset, same as `null`, `undefined` or any other falsy value. So zero becames `100`.
+Here, `height || 100` treats zero height as unset, same as `null`, `undefined` or any other falsy value. So the result is `100`.
 
-The `height ?? 100` returns `100` only if `height` is exactly `null` or `undefined`. So zero remains "as is".
+The `height ?? 100` returns `100` only if `height` is exactly `null` or `undefined`. So the `alert` shows the height value `0` "as is".
 
-Which behavior is better depends on a particular use case. When zero height is a valid value, that we shouldn't touch, then `??` is preferrable.
+Which behavior is better depends on a particular use case. When zero height is a valid value, then `??` is preferrable.
 
 ## Precedence
 

1-js/03-code-quality/04-ninja-code/article.md

@@ -43,7 +43,7 @@ The Dao hides in wordlessness. Only the Dao is well begun and well
 completed.
 ```
 
-Another way to code faster is to use single-letter variable names everywhere. Like `a`, `b` or `c`.
+Another way to code shorter is to use single-letter variable names everywhere. Like `a`, `b` or `c`.
 
 A short variable disappears in the code like a real ninja in the forest. No one will be able to find it using "search" of the editor. And even if someone does, they won't be able to "decipher" what the name `a` or `b` means.
 

1-js/05-data-types/10-destructuring-assignment/article.md

@@ -138,7 +138,7 @@ 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.
-```
+
 
 ### The rest '...'
 

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;
+}

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.
+
+}

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);
+  });
+
+});

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
-```
-

1-js/08-prototypes/04-prototype-methods/article.md

@@ -57,7 +57,6 @@ The descriptors are in the same format as described in the chapter <info:propert
 We can use `Object.create` to perform an object cloning more powerful than copying properties in `for..in`:
 
 ```js
-// fully identical shallow clone of obj
 let clone = Object.create(Object.getPrototypeOf(obj), Object.getOwnPropertyDescriptors(obj));
 ```
 

2-ui/3-event-details/6-pointer-events/article.md

@@ -10,7 +10,7 @@ Let's make a small overview, so that you understand the general picture and the
 
     Then touch devices appeared. For the old code to work, they also generate mouse events. For instance, tapping generates `mousedown`. But mouse events were not good enough, as touch devices are more powerful in many aspects. For example, it's possible to touch multiple points at once, and mouse events don't have any properties for that.
 
-- So touch events were introduced, such as `touchstart`, `touchend`, `touchmove`, that have touch-specific properties (we don't cover them in details here, because pointer events are event better).
+- So touch events were introduced, such as `touchstart`, `touchend`, `touchmove`, that have touch-specific properties (we don't cover them in detail here, because pointer events are even better).
 
     Still, it wasn't enough, as there are many other devices, such as pens, that have their own features. Also, writing a code that listens both touch and mouse events was cumbersome.