mirror of
https://github.com/freeCodeCamp/freeCodeCamp.git
synced 2025-12-20 18:45:55 -05:00
158 lines
2.7 KiB
Markdown
158 lines
2.7 KiB
Markdown
---
|
|
id: 56533eb9ac21ba0edf2244e0
|
|
title: Ersetzen von If-Else-Ketten durch switch
|
|
challengeType: 1
|
|
videoUrl: 'https://scrimba.com/c/c3JE8fy'
|
|
forumTopicId: 18266
|
|
dashedName: replacing-if-else-chains-with-switch
|
|
---
|
|
|
|
# --description--
|
|
|
|
Wenn du viele Optionen zur Auswahl hast, kann eine `switch`-Anweisung einfacher zu schreiben sein als viele verkettete `if`/`else if`-Anweisungen. Das Folgende:
|
|
|
|
```js
|
|
if (val === 1) {
|
|
answer = "a";
|
|
} else if (val === 2) {
|
|
answer = "b";
|
|
} else {
|
|
answer = "c";
|
|
}
|
|
```
|
|
|
|
kann ersetzt werden durch:
|
|
|
|
```js
|
|
switch (val) {
|
|
case 1:
|
|
answer = "a";
|
|
break;
|
|
case 2:
|
|
answer = "b";
|
|
break;
|
|
default:
|
|
answer = "c";
|
|
}
|
|
```
|
|
|
|
# --instructions--
|
|
|
|
Ändere die verketteten `if`/`else if`-Anweisungen in eine `switch`-Anweisung.
|
|
|
|
# --hints--
|
|
|
|
Du solltest nirgendwo im Editor `else`-Anweisungen verwenden
|
|
|
|
```js
|
|
assert(!/else/g.test(code));
|
|
```
|
|
|
|
Du solltest nirgendwo im Editor `if`-Anweisungen verwenden
|
|
|
|
```js
|
|
assert(!/if/g.test(code));
|
|
```
|
|
|
|
Du solltest mindestens vier `break`-Anweisungen verwenden
|
|
|
|
```js
|
|
assert(code.match(/break/g).length >= 4);
|
|
```
|
|
|
|
`chainToSwitch("bob")` sollte den String `Marley` ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch('bob') === 'Marley');
|
|
```
|
|
|
|
`chainToSwitch(42)` sollte den String `The Answer` ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch(42) === 'The Answer');
|
|
```
|
|
|
|
`chainToSwitch(1)` sollte den String `There is no #1` ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch(1) === 'There is no #1');
|
|
```
|
|
|
|
`chainToSwitch(99)` sollte den String `Missed me by this much!` ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch(99) === 'Missed me by this much!');
|
|
```
|
|
|
|
`chainToSwitch(7)` sollte den String `Ate Nine` ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch(7) === 'Ate Nine');
|
|
```
|
|
|
|
`chainToSwitch("John")` sollte `""` (leerer String) ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch('John') === '');
|
|
```
|
|
|
|
`chainToSwitch(156)` sollte `""` (leerer String) ausgeben
|
|
|
|
```js
|
|
assert(chainToSwitch(156) === '');
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
function chainToSwitch(val) {
|
|
let answer = "";
|
|
// Only change code below this line
|
|
|
|
if (val === "bob") {
|
|
answer = "Marley";
|
|
} else if (val === 42) {
|
|
answer = "The Answer";
|
|
} else if (val === 1) {
|
|
answer = "There is no #1";
|
|
} else if (val === 99) {
|
|
answer = "Missed me by this much!";
|
|
} else if (val === 7) {
|
|
answer = "Ate Nine";
|
|
}
|
|
|
|
// Only change code above this line
|
|
return answer;
|
|
}
|
|
|
|
chainToSwitch(7);
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
function chainToSwitch(val) {
|
|
let answer = "";
|
|
|
|
switch (val) {
|
|
case "bob":
|
|
answer = "Marley";
|
|
break;
|
|
case 42:
|
|
answer = "The Answer";
|
|
break;
|
|
case 1:
|
|
answer = "There is no #1";
|
|
break;
|
|
case 99:
|
|
answer = "Missed me by this much!";
|
|
break;
|
|
case 7:
|
|
answer = "Ate Nine";
|
|
}
|
|
return answer;
|
|
}
|
|
```
|