CODEWITHSUNDEEP
javascripthtmlarrays
geek
geek

Reputation: 205

How to randomly select values from array based on starting letter from url

I have an array named items that has 10 url label values.

I have a function which selects 5 values randomly from the array.

I want to make the selection in such a way that the URL starts with first letter w or d

I.E. each item I print to the console should have the url jpej names starting with either w or d

How can I achieve this?

var array2 = [];

var items = [
  {label: 'crow',
   url: 'wcrow.jpg'},
  {label: 'donkey',
    url: 'ddonkey.jpg'},
  {label: 'lion',
  url: 'wlion.jpg'},
  {label: 'dcat',
   url: 'dcat.jpg'},
  {label: 'cheetah',
    url: 'wcheetah.jpg'},
  {label: 'cow',
    url: 'dcow.jpg'},
  {label: 'dog',
    url: 'ddog.jpg'},
  {label: 'horse',
    url: 'dhorse.jpg'},
  {label: 'rabbit',
    url: 'drabbit.jpg'},
  {label: 'elephant',
    url: 'welephant.jpg'},
  {label: 'rose',},
  {label: 'lotus',
    url: 'flotus.jpg'},
  {label: 'jasmine',
    url: 'fjasmine.jpg'},
  {label: 'snake',
    url: 'rsnake.jpg'},
  {label: 'crocodile',
    url: 'rcrocodile.jpg'}];

array2 = items.slice();

function nameselect() {
  for (var index = 0; index < 5; index++) {
    randomIndex = Math.floor(Math.random() * array2.length)

    item = array2[randomIndex];
    array2.splice(randomIndex, 1);


    console.log(item);
  }

}

nameselect();

Upvotes: 2

Views: 53

Answers (2)

Akrion
Akrion

Reputation: 18525

You could also have your startLetters in an separate array and pass it to your random picker function. You could also pass the number of items you want and then do the filtering via Array.filter and Array.includes to get your results:

var items = [{ label: 'crow', url: 'wcrow.jpg' }, { label: 'donkey', url: 'ddonkey.jpg' }, { label: 'lion', url: 'wlion.jpg' }, { label: 'dcat', url: 'dcat.jpg' }, { label: 'cheetah', url: 'wcheetah.jpg' }, { label: 'cow', url: 'dcow.jpg' }, { label: 'dog', url: 'ddog.jpg' }, { label: 'horse', url: 'dhorse.jpg' }, { label: 'rabbit', url: 'drabbit.jpg' }, { label: 'elephant', url: 'welephant.jpg' }, { label: 'rose', }, { label: 'lotus', url: 'flotus.jpg' }, { label: 'jasmine', url: 'fjasmine.jpg' }, { label: 'snake', url: 'rsnake.jpg' }, { label: 'crocodile', url: 'rcrocodile.jpg' } ];

const getRandomUrls = (arr, startLetters, num) => {
  let urls = items.filter(({url}) => url && startLetters.includes(url[0]));
  return [...Array(num)].map(x => urls[Math.floor(Math.random()*urls.length)])
}

console.log(getRandomUrls(items, ['w', 'd'], 5))

Upvotes: 1

CertainPerformance
CertainPerformance

Reputation: 371019

First filter the array by its url before selecting the random index. One option is

const itemsWithWOrD = items.filter(({ url }) => /^[wd]/i.test(url));

Then, in the loop, make sure to declare your variables with const, let, or var to avoid implicitly creating a global variable:

for (let index = 0; index < 5; index++) {
  const randomIndex = Math.floor(Math.random() * array2.length);
  const [item] = itemsWithWOrD.splice(randomIndex, 1);
  console.log(item);
}

If you don't like regular expressions, an alternative is to use two startsWiths:

const itemsWithWOrD = items.filter(({ url }) => url && (url.startsWith('w') || url.startsWith('d')));


var array2 = [];

var items = [{
    label: 'crow',
    url: 'wcrow.jpg'
  },
  {
    label: 'donkey',
    url: 'ddonkey.jpg'
  },
  {
    label: 'lion',
    url: 'wlion.jpg'
  },
  {
    label: 'dcat',
    url: 'dcat.jpg'
  },
  {
    label: 'cheetah',
    url: 'wcheetah.jpg'
  },
  {
    label: 'cow',
    url: 'dcow.jpg'
  },
  {
    label: 'dog',
    url: 'ddog.jpg'
  },
  {
    label: 'horse',
    url: 'dhorse.jpg'
  },
  {
    label: 'rabbit',
    url: 'drabbit.jpg'
  },
  {
    label: 'elephant',
    url: 'welephant.jpg'
  },
  {
    label: 'rose',
  },
  {
    label: 'lotus',
    url: 'flotus.jpg'
  },
  {
    label: 'jasmine',
    url: 'fjasmine.jpg'
  },
  {
    label: 'snake',
    url: 'rsnake.jpg'
  },
  {
    label: 'crocodile',
    url: 'rcrocodile.jpg'
  }
];

function nameselect() {
  const itemsWithWOrD = items.filter(({ url }) => /^[wd]/i.test(url));
  for (let index = 0; index < 5; index++) {
    const randomIndex = Math.floor(Math.random() * array2.length);
    const [item] = itemsWithWOrD.splice(randomIndex, 1);
    console.log(item);
  }
}

nameselect();

Upvotes: 1

Related Questions