Extract first element from Nested Array in JSON NodeJS

Question

I'm trying to grab the nested array called platforms, but i only want the first key in there. So for the Array it should be like [{platforms: [windows], [windows]]} instead of [{platforms: [windows, osx, linux, null], [windows, null, null, null]]} Is this even achievable? I looked through .map and .filter but can't seem to just grab the first piece of the array.

Example ARRAY

[{ id: 1,
game: { position: 1},
platforms: [ 'windows', 'osx', 'linux', null ],
title: 'xxx',
user: {
  url: 'xxxx',
  name: 'xxx',
  id: 1
}
},{ id: 2,
game: { position: 2},
platforms: [ 'windows', null, null, null, ],
title: 'xxx',
user: {
  url: 'xxxx',
  name: 'xxx',
  id: 2
}
]

How can I handle this in Javascript / NodeJS

var result = body.games.filter(a=>a).reduce((acc, a) => {
    return acc.concat(a)
}, []).map(a=>a.platforms);
console.log(result);

Result = [ 'windows', 'osx', 'linux' null ], [ 'windows', null, null, null ],

eol · Accepted Answer · 2020-07-07 14:34:56Z

1

A simple .map should do this:

function mapPlatform(data) {
  return data.map(entry => Array.isArray(entry.platforms) ? entry.platforms[0] : 'no platform data available')
}

const data = [{id:1,game:{position:1},platforms:['windows','osx','linux',null],title:'xxx',user:{url:'xxxx',name:'xxx',id:1,},},{id:2,game:{position:2},platforms:['windows',null,null,null],title:'xxx',user:{url:'xxxx',name:'xxx',id:2,},}];
console.log(mapPlatform(data));

edited Jul 7, 2020 at 14:34

answered Jul 7, 2020 at 14:08

eol

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7 Comments

askmeaquestion1234 Over a year ago

frustrating! I've done this before and i get TypeError: Cannot read property '0' of undefined. However using your data const it works. There must be something wrong with my json output that i'm trying to pull from.

askmeaquestion1234 Over a year ago

console.log(body.games.map(entry => entry.platforms)); gives me [ [ 'windows', 'osx', 'linux' ], [ 'windows', 'osx', 'linux' ], ] But if i do platforms[0] i get undefined..

eol Over a year ago

Well, the one you've added to the question is invalid, yes. It is missing a } before ].

askmeaquestion1234 Over a year ago

ok any idea on how to append that to my json to make it valid? I'll mark your answer as correct regardless, as you are right!

eol Over a year ago

It would be preferable to make sure that the json is valid in the first place, instead of manually fixing it - where are you reading the data from?

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