freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/es6/write-arrow-functions-with-parameters.english.md

id	title	challengeType
587d7b88367417b2b2512b44	Write Arrow Functions with Parameters	1

Description

Just like a normal function, you can pass arguments into arrow functions.

// doubles input value and returns it
const doubler = (item) => item * 2;

You can pass more than one argument into arrow functions as well.

Instructions

Rewrite the myConcat function which appends contents of arr2 to arr1 so that the function uses arrow function syntax.

Tests

tests:
  - text: User did replace <code>var</code> keyword.
    testString: getUserInput => assert(!getUserInput('index').match(/var/g), 'User did replace <code>var</code> keyword.');
  - text: <code>myConcat</code> should be a constant variable (by using <code>const</code>).
    testString: getUserInput => assert(getUserInput('index').match(/const\s+myConcat/g), '<code>myConcat</code> should be a constant variable (by using <code>const</code>).');
  - text: <code>myConcat</code> should be a function
    testString: assert(typeof myConcat === 'function', '<code>myConcat</code> should be a function');
  - text: <code>myConcat()</code> returns the correct <code>array</code>
    testString: assert(() => { const a = myConcat([1], [2]); return a[0] == 1 && a[1] == 2; }, '<code>myConcat()</code> returns the correct <code>array</code>');
  - text: <code>function</code> keyword was not used.
    testString: getUserInput => assert(!getUserInput('index').match(/function/g), '<code>function</code> keyword was not used.');

Challenge Seed

var myConcat = function(arr1, arr2) {
  "use strict";
  return arr1.concat(arr2);
};
// test your code
console.log(myConcat([1, 2], [3, 4, 5]));

Solution

const myConcat = (arr1, arr2) =>  {
  "use strict";
  return arr1.concat(arr2);
};
// test your code
console.log(myConcat([1, 2], [3, 4, 5]));