CODEWITHSUNDEEP
javascriptarraysjavascript-objects
Tucker
Tucker

Reputation: 245

Returning Object Value Based On Property

I have an object that includes a variety of animals:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}]

I'm wanting to return the names of the animals that are cats, only. I'm struggling to do so. Here is my attempt:

var cats = []
function onlyCats(array) {
  if (toonimals.animal === 'cat') {
    cats.push(toonimals.name)
  }
  return cats
}
console.log(onlyCats(toonimals));

Currently, it is only returning the empty array so the .push() method isn't working for some reason.

Thank you in advance.

Upvotes: 2

Views: 103

Answers (5)

Amardeep Bhowmick
Amardeep Bhowmick

Reputation: 16908

Use Array.filter to filter objects having name === 'cat' and Array.from to transform the result and get a new array from the filtered array.

const toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}];

let catOnly = Array.from(toonimals.filter(obj => obj.animal === 'cat'), animal => animal.name);

console.log(catOnly);

Upvotes: 0

Jack Bashford
Jack Bashford

Reputation: 44145

You can just use one map, then filter by Boolean to remove undefined:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}];

const catNames = arr => arr.map(e => { if (e.animal == "cat") return e.name }).filter(Boolean);

console.log(catNames(toonimals));

Upvotes: 0

Mamun
Mamun

Reputation: 68933

You have to loop through the array to filter() the animal. Then use map() to modify the array to return the name:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}];

function onlyCats(array) {
  return array.filter(a => a.animal === 'cat').map(a => a.name);
}
console.log(onlyCats(toonimals));

In your way with the help of forEach():

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}];

var cats = []
function onlyCats(array) {
  array.forEach(function(animal){
    if (animal.animal === 'cat') {
      cats.push(animal.name)
    }
  });
  return cats;
}
console.log(onlyCats(toonimals));

Upvotes: 1

Code Maniac
Code Maniac

Reputation: 37775

You can use forEach 

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}]
let op = []

toonimals.forEach(({name,animal})=>{
  if(animal === 'cat'){
    op.push(name)
  }
})

console.log(op)

You can also use filter and map.

by filter we get object with animal = cat and than we map name of each filtered element. 

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}]

let cats = toonimals.filter(({animal})=> animal ==='cat').map(({name})=>name)

console.log(cats)

Upvotes: 1

CertainPerformance
CertainPerformance

Reputation: 371168

You need to actually iterate over the toonimals array. You can achieve this concisely with .filter and .map:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}]

const onlyCats = array => array
  .filter(({ animal }) => animal === 'cat')
  .map(({ name }) => name);
  
console.log(onlyCats(toonimals));

Or, to only iterate once, use reduce:

var toonimals = [ {name: 'Itchy', animal: 'mouse'}, {name: 'Stimpy', animal: 'cat'}, {name: 'Daffy', animal: 'duck'}, {name: 'Scratchy', animal: 'cat'}, {name: 'Ren', animal: 'dog'}, {name: 'Felix', animal: 'cat'}]

const onlyCats = array => array
  .reduce((a, { name, animal }) => {
    if (animal === 'cat') {
      a.push(name);
    }
    return a;
  }, []);
console.log(onlyCats(toonimals));

Upvotes: 1

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