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>
94 lines
1.9 KiB
Markdown
94 lines
1.9 KiB
Markdown
---
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id: 587d7b88367417b2b2512b44
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title: Write Arrow Functions with Parameters
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challengeType: 1
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forumTopicId: 301223
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dashedName: write-arrow-functions-with-parameters
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---
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# --description--
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Just like a regular function, you can pass arguments into an arrow function.
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```js
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// doubles input value and returns it
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const doubler = (item) => item * 2;
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doubler(4); // returns 8
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```
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If an arrow function has a single parameter, the parentheses enclosing the parameter may be omitted.
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```js
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// the same function, without the parameter parentheses
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const doubler = item => item * 2;
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```
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It is possible to pass more than one argument into an arrow function.
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```js
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// multiplies the first input value by the second and returns it
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const multiplier = (item, multi) => item * multi;
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multiplier(4, 2); // returns 8
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```
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# --instructions--
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Rewrite the `myConcat` function which appends contents of `arr2` to `arr1` so that the function uses arrow function syntax.
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# --hints--
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You should replace the `var` keyword.
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```js
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(getUserInput) => assert(!getUserInput('index').match(/var/g));
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```
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`myConcat` should be a constant variable (by using `const`).
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```js
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(getUserInput) => assert(getUserInput('index').match(/const\s+myConcat/g));
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```
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`myConcat` should be an arrow function with two parameters
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```js
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assert(
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/myConcat=\(\w+,\w+\)=>/.test(code.replace(/\s/g, '')) &&
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typeof myConcat === 'function'
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);
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```
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`myConcat()` should return `[1, 2, 3, 4, 5]`.
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```js
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assert.deepEqual(myConcat([1, 2], [3, 4, 5]), [1, 2, 3, 4, 5]);
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```
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`function` keyword should not be used.
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```js
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(getUserInput) => assert(!getUserInput('index').match(/function/g));
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```
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# --seed--
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## --seed-contents--
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```js
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var myConcat = function(arr1, arr2) {
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return arr1.concat(arr2);
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};
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console.log(myConcat([1, 2], [3, 4, 5]));
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```
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# --solutions--
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```js
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const myConcat = (arr1, arr2) => {
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return arr1.concat(arr2);
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};
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console.log(myConcat([1, 2], [3, 4, 5]));
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```
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