64 lines
1.5 KiB
Markdown
64 lines
1.5 KiB
Markdown
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---
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id: 587d7b8c367417b2b2512b58
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title: Create an Export Fallback with export default
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challengeType: 1
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forumTopicId: 301199
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dashedName: create-an-export-fallback-with-export-default
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---
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# --description--
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In the `export` lesson, you learned about the syntax referred to as a <dfn>named export</dfn>. This allowed you to make multiple functions and variables available for use in other files.
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There is another `export` syntax you need to know, known as <dfn>export default</dfn>. Usually you will use this syntax if only one value is being exported from a file. It is also used to create a fallback value for a file or module.
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Below are examples using `export default`:
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```js
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// named function
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export default function add(x, y) {
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return x + y;
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}
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// anonymous function
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export default function(x, y) {
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return x + y;
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}
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```
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Since `export default` is used to declare a fallback value for a module or file, you can only have one value be a default export in each module or file. Additionally, you cannot use `export default` with `var`, `let`, or `const`
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# --instructions--
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The following function should be the fallback value for the module. Please add the necessary code to do so.
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# --hints--
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Your code should use `export` fallback.
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```js
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assert(
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code.match(
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/export\s+default\s+function(\s+subtract\s*|\s*)\(\s*x,\s*y\s*\)\s*{/g
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)
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);
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```
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# --seed--
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## --seed-contents--
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```js
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function subtract(x, y) {
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return x - y;
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}
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```
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# --solutions--
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```js
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export default function subtract(x, y) {
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return x - y;
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}
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```
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