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Ilya Kantor 2017-05-10 16:41:49 +03:00
parent 14a882fee0
commit c56693bca8
3 changed files with 9 additions and 8 deletions
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13
1-js/02-first-steps/13-switch/article.md
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@ -90,7 +90,7 @@ alert( "I don't know such values" );
```
````smart header="Any expresion can be a `switch/case` argument"
Both `switch` and case allow arbitrary expresions.
Both `switch` and case allow arbitrary expressions.
For example:
@ -101,14 +101,15 @@ let b = 0;
switch (+a) {
*!*
case b + 1:
alert( 1 );
alert("this runs, because +a is 1, exactly equals b+1");
break;
*/!*
default:
alert('no-no, see the code above, it executes');
alert("this doesn't run");
}
```
Here `+a` gives `1`, that's compared with `b + 1` in `case`, and the corresponding code is executed.
````
## Grouping of "case"
@ -129,7 +130,7 @@ switch (a) {
case 3: // (*) grouped two cases
case 5:
alert('Wrong!');
alert('Why don't you take a math class?');
alert("Why don't you take a math class?");
break;
*/!*
@ -144,7 +145,7 @@ The ability to "group" cases a side-effect of how `switch/case` works without `b
## Type matters
Let's emphase that the equality check is always strict. The values must be of the same type to match.
Let's emphasize that the equality check is always strict. The values must be of the same type to match.
For example, let's consider the code:
@ -169,4 +170,4 @@ switch (arg) {
1. For `0`, `1`, the first `alert` runs.
2. For `2` the second `alert` runs.
3. But for `3`, the result of the `prompt` is a string `"3"`, which is not strictly equal `===` to the number `3`. So we've got a dead code in `case 3`! The `default` variant will execite.
3. But for `3`, the result of the `prompt` is a string `"3"`, which is not strictly equal `===` to the number `3`. So we've got a dead code in `case 3`! The `default` variant will execute.