freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/es6/create-an-export-fallback-with-export-default.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
587d7b8c367417b2b2512b58	Create an Export Fallback with export default	1	301199	create-an-export-fallback-with-export-default

--description--

In the export lesson, you learned about the syntax referred to as a named export. This allowed you to make multiple functions and variables available for use in other files.

There is another export syntax you need to know, known as export default. 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.

Below are examples using export default:

// named function
export default function add(x, y) {
  return x + y;
}

// anonymous function
export default function(x, y) {
  return x + y;
}

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

--instructions--

The following function should be the fallback value for the module. Please add the necessary code to do so.

--hints--

Your code should use export fallback.

assert(
  code.match(
    /export\s+default\s+function(\s+subtract\s*|\s*)\(\s*x,\s*y\s*\)\s*{/g
  )
);

--seed--

--seed-contents--

function subtract(x, y) {
  return x - y;
}

--solutions--

export default function subtract(x, y) {
  return x - y;
}