How to create a new array from another one?

Question

I have one array:

const animals = ['cat', 'dog', 'cow', 'horse']

And second one:

const animalsWithNames = ['cat:mik', 'dog', 'horse:lucy']

And I need to create a function that gives me in a result a third array:

const result = ['cat', 'dog', 'horse']

So, as well I understad I have to map first array and check by function. If piece of string exist in first array's item it should be in the result one. Am I right? Please about tips or proposal solutions.

My attempt:

const checkStr = str => animalsWithNames.forEach(el => {
        if (el.substring(0, str.length) === str) {
            return str
        }
    })

const result = animals.map(el => checkStr(el))
console.log(result)

What you understand is correct, can you show us an attempt at a solution? — M0nst3R
– M0nst3R, Commented Sep 17, 2021 at 10:43

Mamun · Accepted Answer · 2021-09-17 10:47:29Z

3

You can try using Array.prototype.filter() and Array.prototype.some() like the following way:

const animals = ['cat', 'dog', 'cow', 'horse'];
const animalsWithNames = ['cat:mik', 'dog', 'horse:lucy'];
const result = animals.filter(a => animalsWithNames.some(an => an.split(':')[0] == a));
console.log(result);

answered Sep 17, 2021 at 10:47

Mamun

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1 Comment

Mamun Over a year ago

@karolina-szlenk, you are most welcome:)

Nitheesh · Accepted Answer · 2021-09-17 10:51:42Z

1

Just use Array.reduce with looping through first array and checking the nodes is present in second.

const animals = ['cat', 'dog', 'cow', 'horse'];
const animalsWithNames = ['cat:mik', 'dog', 'horse:lucy'];
const result = animals.reduce((acc, curr) => {
  const node = animalsWithNames.find(item => item.indexOf(curr) > -1);
  if (node) {
    acc.push(curr)
  }
  return acc;
}, []);
console.log(result);

edited Sep 17, 2021 at 10:51

answered Sep 17, 2021 at 10:43

Nitheesh

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1 Comment

M0nst3R Over a year ago

The author wants to filter the first array by the contents of the second array, not just filter away values after the :.

Alan Omar · Accepted Answer · 2021-09-17 10:49:16Z

0

const animals = ['cat', 'dog', 'cow', 'horse']
const animalsWithNames = ['cat:mik', 'dog', 'horse:lucy']

const names = animalsWithNames.map(e => e.split(":")[0])
const result = names.filter(e => animals.includes(e))

console.log(result)

answered Sep 17, 2021 at 10:49

Alan Omar

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