129 lines
2.7 KiB
Markdown
129 lines
2.7 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244be
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title: Global Scope and Functions
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cQM7mCN'
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forumTopicId: 18193
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dashedName: global-scope-and-functions
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---
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# --description--
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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.
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Variables which are declared without the `let` or `const` keywords 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 `let` or `const`.
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# --instructions--
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Using `let` or `const`, declare a global variable named `myGlobal` outside of any function. Initialize it with a value of `10`.
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Inside function `fun1`, assign `5` to `oopsGlobal` ***without*** using the `let` or `const` keywords.
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# --hints--
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`myGlobal` should be defined
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```js
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assert(typeof myGlobal != 'undefined');
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```
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`myGlobal` should have a value of `10`
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```js
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assert(myGlobal === 10);
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```
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`myGlobal` should be declared using the `let` or `const` keywords
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```js
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assert(/(let|const)\s+myGlobal/.test(code));
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```
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`oopsGlobal` should be a global variable and have a value of `5`
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```js
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assert(typeof oopsGlobal != 'undefined' && oopsGlobal === 5);
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```
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# --seed--
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## --before-user-code--
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```js
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var logOutput = "";
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var originalConsole = console
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function capture() {
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var nativeLog = console.log;
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console.log = function (message) {
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logOutput = message;
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if(nativeLog.apply) {
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nativeLog.apply(originalConsole, arguments);
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} else {
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var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
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nativeLog(nativeMsg);
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}
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};
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}
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function uncapture() {
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console.log = originalConsole.log;
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}
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var oopsGlobal;
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capture();
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```
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## --after-user-code--
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```js
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fun1();
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fun2();
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uncapture();
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(function() { return logOutput || "console.log never called"; })();
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```
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## --seed-contents--
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```js
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// Declare the myGlobal variable below this line
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function fun1() {
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// Assign 5 to oopsGlobal Here
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}
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// Only change code above this line
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function fun2() {
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var output = "";
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if (typeof myGlobal != "undefined") {
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output += "myGlobal: " + myGlobal;
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}
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if (typeof oopsGlobal != "undefined") {
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output += " oopsGlobal: " + oopsGlobal;
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}
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console.log(output);
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}
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```
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# --solutions--
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```js
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const myGlobal = 10;
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function fun1() {
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oopsGlobal = 5;
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}
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function fun2() {
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var output = "";
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if(typeof myGlobal != "undefined") {
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output += "myGlobal: " + myGlobal;
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}
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if(typeof oopsGlobal != "undefined") {
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output += " oopsGlobal: " + oopsGlobal;
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}
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console.log(output);
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}
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```
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