140 lines
3.1 KiB
Markdown
140 lines
3.1 KiB
Markdown
---
|
|
id: 56533eb9ac21ba0edf2244e0
|
|
title: Replacing If Else Chains with Switch
|
|
challengeType: 1
|
|
videoUrl: 'https://scrimba.com/c/c3JE8fy'
|
|
forumTopicId: 18266
|
|
---
|
|
|
|
## Description
|
|
<section id='description'>
|
|
If you have many options to choose from, a <code>switch</code> statement can be easier to write than many chained <code>if</code>/<code>else if</code> statements. The following:
|
|
|
|
```js
|
|
if (val === 1) {
|
|
answer = "a";
|
|
} else if (val === 2) {
|
|
answer = "b";
|
|
} else {
|
|
answer = "c";
|
|
}
|
|
```
|
|
|
|
can be replaced with:
|
|
|
|
```js
|
|
switch(val) {
|
|
case 1:
|
|
answer = "a";
|
|
break;
|
|
case 2:
|
|
answer = "b";
|
|
break;
|
|
default:
|
|
answer = "c";
|
|
}
|
|
```
|
|
|
|
</section>
|
|
|
|
## Instructions
|
|
<section id='instructions'>
|
|
Change the chained <code>if</code>/<code>else if</code> statements into a <code>switch</code> statement.
|
|
</section>
|
|
|
|
## Tests
|
|
<section id='tests'>
|
|
|
|
```yml
|
|
tests:
|
|
- text: You should not use any <code>else</code> statements anywhere in the editor
|
|
testString: assert(!/else/g.test(code));
|
|
- text: You should not use any <code>if</code> statements anywhere in the editor
|
|
testString: assert(!/if/g.test(code));
|
|
- text: You should have at least four <code>break</code> statements
|
|
testString: assert(code.match(/break/g).length >= 4);
|
|
- text: <code>chainToSwitch("bob")</code> should be "Marley"
|
|
testString: assert(chainToSwitch("bob") === "Marley");
|
|
- text: <code>chainToSwitch(42)</code> should be "The Answer"
|
|
testString: assert(chainToSwitch(42) === "The Answer");
|
|
- text: "<code>chainToSwitch(1)</code> should be \"There is no #1\""
|
|
testString: "assert(chainToSwitch(1) === \"There is no #1\");"
|
|
- text: <code>chainToSwitch(99)</code> should be "Missed me by this much!"
|
|
testString: assert(chainToSwitch(99) === "Missed me by this much!");
|
|
- text: <code>chainToSwitch(7)</code> should be "Ate Nine"
|
|
testString: assert(chainToSwitch(7) === "Ate Nine");
|
|
- text: <code>chainToSwitch("John")</code> should be "" (empty string)
|
|
testString: assert(chainToSwitch("John") === "");
|
|
- text: <code>chainToSwitch(156)</code> should be "" (empty string)
|
|
testString: assert(chainToSwitch(156) === "");
|
|
|
|
```
|
|
|
|
</section>
|
|
|
|
## Challenge Seed
|
|
<section id='challengeSeed'>
|
|
|
|
<div id='js-seed'>
|
|
|
|
```js
|
|
function chainToSwitch(val) {
|
|
var 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);
|
|
|
|
```
|
|
|
|
</div>
|
|
|
|
|
|
|
|
</section>
|
|
|
|
## Solution
|
|
<section id='solution'>
|
|
|
|
|
|
```js
|
|
function chainToSwitch(val) {
|
|
var 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;
|
|
}
|
|
```
|
|
|
|
</section>
|