JavaScript Array map() method do not work

import data from './data.json';

const URL = `${data.resources.map((el, index) => el.url)}`;

// data +  "resources" + map(el, index) => element + "url"

data.json

{  "resources": [ {      "title": "",      "link": "",      "url": "https://site.com/folder"     } ] }

// add / at the end => /folder/ ===OR=== remove / from the end => /folder

{[...Array(n)].map((el, index) => (

<div key={index} className=''>{el}</div>

))}

// ...Array above can be used to repeat [0] element n times

// remove duplicates within a map function =>

<div class="tags">
  {posts.map(post =>
    [...new Set(post.frontmatter.tags)].map(tag => (
      <Link
        key={tag + `tag`}
        to={`/tags/${kebabCase(tag)}/`}
        className="tag is light"
      >
        {tag}
      </Link>
    ))
  )}
</div>

https://stackoverflow.com/questions/65512907/remove-duplicates-within-a-map-function