fixes

1-js/02-first-steps/06-type-conversions/1-primitive-conversions-questions/solution.md

@@ -14,6 +14,7 @@ true + false = 1
 " -9  " - 5 = -14 // (4)
 null + 1 = 1 // (5)
 undefined + 1 = NaN // (6)
+" \t \n" - 2 = -2 // (7)
 ```
 
 1. The addition with a string `"" + 1` converts `1` to a string: `"" + 1 = "1"`, and then we have `"1" + 0`, the same rule is applied.
@@ -22,3 +23,4 @@ undefined + 1 = NaN // (6)
 4. The subtraction always converts to numbers, so it makes `"  -9  "` a number `-9` (ignoring spaces around it).
 5. `null` becomes `0` after the numeric conversion.
 6. `undefined` becomes `NaN` after the numeric conversion.
+7. Space characters, such as `\t` and `\n`, are trimmed off string start and end when a string is converted to a number. So a string `\t \n`, similarly to an empty string, becomes `0`.

1-js/02-first-steps/06-type-conversions/1-primitive-conversions-questions/task.md

@@ -21,6 +21,7 @@ true + false
 "  -9  " - 5
 null + 1
 undefined + 1
+" \t \n" - 2
 ```
 
 Think well, write down and then compare with the answer.

1-js/05-data-types/05-array-methods/article.md

@@ -119,7 +119,7 @@ The method [arr.slice](mdn:js/Array/slice) is much simpler than similar-looking
 The syntax is:
 
 ```js
-arr.slice(start, end)
+arr.slice([start], [end])
 ```
 
 It returns a new array copying to it all items from index `start` to `end` (not including `end`). Both `start` and `end` can be negative, in that case position from array end is assumed.
@@ -136,6 +136,8 @@ alert( arr.slice(1, 3) ); // e,s (copy from 1 to 3)
 alert( arr.slice(-2) ); // s,t (copy from -2 till the end)
 ```
 
+We can also call it without arguments: `arr.slice()` creates a copy of `arr`. That's often used to obtain a copy for further transformations that should not affect the original array.
+
 ### concat
 
 The method [arr.concat](mdn:js/Array/concat) creates a new array that includes values from other arrays and additional items.