ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
129 lines
2.7 KiB
Markdown
129 lines
2.7 KiB
Markdown
---
|
|
id: 56533eb9ac21ba0edf2244be
|
|
title: Global Scope and Functions
|
|
challengeType: 1
|
|
videoUrl: 'https://scrimba.com/c/cQM7mCN'
|
|
forumTopicId: 18193
|
|
dashedName: global-scope-and-functions
|
|
---
|
|
|
|
# --description--
|
|
|
|
In JavaScript, <dfn>scope</dfn> refers to the visibility of variables. Variables which are defined outside of a function block have <dfn>Global</dfn> scope. This means, they can be seen everywhere in your JavaScript code.
|
|
|
|
Variables which are used without the `var` keyword are automatically created in the `global` scope. This can create unintended consequences elsewhere in your code or when running a function again. You should always declare your variables with `var`.
|
|
|
|
# --instructions--
|
|
|
|
Using `var`, declare a global variable named `myGlobal` outside of any function. Initialize it with a value of `10`.
|
|
|
|
Inside function `fun1`, assign `5` to `oopsGlobal` ***without*** using the `var` keyword.
|
|
|
|
# --hints--
|
|
|
|
`myGlobal` should be defined
|
|
|
|
```js
|
|
assert(typeof myGlobal != 'undefined');
|
|
```
|
|
|
|
`myGlobal` should have a value of `10`
|
|
|
|
```js
|
|
assert(myGlobal === 10);
|
|
```
|
|
|
|
`myGlobal` should be declared using the `var` keyword
|
|
|
|
```js
|
|
assert(/var\s+myGlobal/.test(code));
|
|
```
|
|
|
|
`oopsGlobal` should be a global variable and have a value of `5`
|
|
|
|
```js
|
|
assert(typeof oopsGlobal != 'undefined' && oopsGlobal === 5);
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --before-user-code--
|
|
|
|
```js
|
|
var logOutput = "";
|
|
var originalConsole = console
|
|
function capture() {
|
|
var nativeLog = console.log;
|
|
console.log = function (message) {
|
|
logOutput = message;
|
|
if(nativeLog.apply) {
|
|
nativeLog.apply(originalConsole, arguments);
|
|
} else {
|
|
var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
|
|
nativeLog(nativeMsg);
|
|
}
|
|
};
|
|
}
|
|
|
|
function uncapture() {
|
|
console.log = originalConsole.log;
|
|
}
|
|
var oopsGlobal;
|
|
capture();
|
|
```
|
|
|
|
## --after-user-code--
|
|
|
|
```js
|
|
fun1();
|
|
fun2();
|
|
uncapture();
|
|
(function() { return logOutput || "console.log never called"; })();
|
|
```
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
// Declare the myGlobal variable below this line
|
|
|
|
|
|
function fun1() {
|
|
// Assign 5 to oopsGlobal Here
|
|
|
|
}
|
|
|
|
// Only change code above this line
|
|
|
|
function fun2() {
|
|
var output = "";
|
|
if (typeof myGlobal != "undefined") {
|
|
output += "myGlobal: " + myGlobal;
|
|
}
|
|
if (typeof oopsGlobal != "undefined") {
|
|
output += " oopsGlobal: " + oopsGlobal;
|
|
}
|
|
console.log(output);
|
|
}
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
var myGlobal = 10;
|
|
|
|
function fun1() {
|
|
oopsGlobal = 5;
|
|
}
|
|
|
|
function fun2() {
|
|
var output = "";
|
|
if(typeof myGlobal != "undefined") {
|
|
output += "myGlobal: " + myGlobal;
|
|
}
|
|
if(typeof oopsGlobal != "undefined") {
|
|
output += " oopsGlobal: " + oopsGlobal;
|
|
}
|
|
console.log(output);
|
|
}
|
|
```
|