101 lines
2.2 KiB
Markdown
101 lines
2.2 KiB
Markdown
---
|
|
id: 56bbb991ad1ed5201cd392cf
|
|
title: Write Reusable JavaScript with Functions
|
|
challengeType: 1
|
|
videoUrl: 'https://scrimba.com/c/cL6dqfy'
|
|
forumTopicId: 18378
|
|
---
|
|
|
|
# --description--
|
|
|
|
In JavaScript, we can divide up our code into reusable parts called <dfn>functions</dfn>.
|
|
|
|
Here's an example of a function:
|
|
|
|
```js
|
|
function functionName() {
|
|
console.log("Hello World");
|
|
}
|
|
```
|
|
|
|
You can call or <dfn>invoke</dfn> this function by using its name followed by parentheses, like this: `functionName();` Each time the function is called it will print out the message `"Hello World"` on the dev console. All of the code between the curly braces will be executed every time the function is called.
|
|
|
|
# --instructions--
|
|
|
|
<ol><li>Create a function called <code>reusableFunction</code> which prints <code>"Hi World"</code> to the dev console.</li><li>Call the function.</li></ol>
|
|
|
|
# --hints--
|
|
|
|
`reusableFunction` should be a function.
|
|
|
|
```js
|
|
assert(typeof reusableFunction === 'function');
|
|
```
|
|
|
|
`reusableFunction` should output "Hi World" to the dev console.
|
|
|
|
```js
|
|
assert(hiWorldWasLogged);
|
|
```
|
|
|
|
You should call `reusableFunction` after you define it.
|
|
|
|
```js
|
|
assert(/^\s*reusableFunction\(\)\s*/m.test(code));
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --before-user-code--
|
|
|
|
```js
|
|
var logOutput = "";
|
|
var originalConsole = console;
|
|
var nativeLog = console.log;
|
|
var hiWorldWasLogged = false;
|
|
function capture() {
|
|
console.log = function (message) {
|
|
if(message === 'Hi World') hiWorldWasLogged = true;
|
|
if(message && message.trim) logOutput = message.trim();
|
|
if(nativeLog.apply) {
|
|
nativeLog.apply(originalConsole, arguments);
|
|
} else {
|
|
var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
|
|
nativeLog(nativeMsg);
|
|
}
|
|
};
|
|
}
|
|
|
|
function uncapture() {
|
|
console.log = nativeLog;
|
|
}
|
|
|
|
capture();
|
|
```
|
|
|
|
## --after-user-code--
|
|
|
|
```js
|
|
uncapture();
|
|
|
|
if (typeof reusableFunction !== "function") {
|
|
(function() { return "reusableFunction is not defined"; })();
|
|
} else {
|
|
(function() { return logOutput || "console.log never called"; })();
|
|
}
|
|
```
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
function reusableFunction() {
|
|
console.log("Hi World");
|
|
}
|
|
reusableFunction();
|
|
```
|