如何随机化我从 GET 请求中的 JSON 响应中提取的对象

Question

I'm very new to coding and working through a course on Javascript. As part of the Requests project, I needed to pull venue information using Foursquare's API. As it sits, it pulls from the array in order as it appears. I'm trying to randomize which venue it pulls. Here is my GET request block:

const getVenues = async () => {
  const city = $input.val();
  const urlToFetch = `${url}${city}&limit=10&client_id=${clientId}&client_secret=${clientSecret}&v=20210712`;

  try {
    const response = await fetch(urlToFetch);
    if(response.ok) {
      const jsonResponse = await response.json();
      const venues = jsonResponse.response.groups[0].items.map(item => item.venue);
      console.log(jsonResponse);
      return venues;
    };
  }
  catch(error) {console.log(error)};
};

My goal is to randomize the object from the array in the 'items' parameter. I've tried setting the venues variable to

const venues = Math.floor(Math.random(jsonResponse...)*10)

but this doesn't work. Thanks

Answer 1

I would suggest using a Fisher-Yates shuffle to randomize array items.

I've used an implementation from here , thanks to the author bubnicbf

We'll grab the items as normal, then pass our venues array to the FisherYatesShuffle function to randomize them.

 // https://github.com/bubnicbf/Fisher-Yates-shuffle/blob/master/Fisher-Yates.js function FisherYatesShuffle(a) { var n = a.length, r, temp; while (n > 1) { r = Math.floor(n * Math.random()); n -= 1; temp = a[n]; a[n] = a[r]; a[r] = temp; } return a; } // Assign values to allow function to run... $input = { val() {} } url = '' city = '' clientId = '' clientSecret = '' const getVenues = async () => { const city = $input.val(); const urlToFetch = `${url}${city}&limit=10&client_id=${clientId}&client_secret=${clientSecret}&v=20210712`; try { const response = await fetch(urlToFetch); if(response.ok) { const jsonResponse = await response.json(); const venues = jsonResponse.response.groups[0].items.map(item => item.venue); console.log('Venues (unshuffled):', venues); // Randomize our venues const shuffledVenues = FisherYatesShuffle(venues); console.log('Venues (shuffled):', shuffledVenues); return shuffledVenues; }; } catch(error) {console.log(error)}; }; // Call the service getVenues() // Mocked version of fetch, for demonstration purposes. function fetch() { const response = { ok: true, json() { return { response: { groups: [ { items: [ { venue: 'Venue 1'}, { venue: 'Venue 2'}, { venue: 'Venue 3'}, { venue: 'Venue 4'}, { venue: 'Venue 5'} ] } ] } } } } return new Promise(resolve => { setTimeout(resolve, 100, response) }) }

And a simpler demonstration is below, showing us shuffling our venues array:

 function FisherYatesShuffle(a) { var n = a.length, r, temp; while (n > 1) { r = Math.floor(n * Math.random()); n -= 1; temp = a[n]; a[n] = a[r]; a[r] = temp; } return a; } const venues = [ { venue: 'Venue 1'}, { venue: 'Venue 2'}, { venue: 'Venue 3'}, { venue: 'Venue 4'}, { venue: 'Venue 5'} ]; console.log("Venues:", venues); console.log("Venues (shuffled):", FisherYatesShuffle(venues));

And last, but not least there is a lodash shuffle function as well (that uses a version of Fisher-Yates)

 const venues = [ { venue: 'Venue 1'}, { venue: 'Venue 2'}, { venue: 'Venue 3'}, { venue: 'Venue 4'}, { venue: 'Venue 5'} ]; console.log("Venues:", venues); console.log("Venues (shuffled):", _.shuffle(venues))

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js" integrity="sha512-WFN04846sdKMIP5LKNphMaWzU7YpMyCU245etK3g/2ARYbPK9Ub18eG+ljU96qKRCWh+quCY7yefSmlkQw1ANQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>