get length of json array of objects that match a specific string

Question

Say I have an array of objects called friends

let friends = [
    {"name": "test 1", "type": "pending"}, 
    {"name": "test 2", "type": "friends"}, 
    {"name": "test 3", "type": "friends"},
    {"name": "test 4", "type": "friends"},
    {"name": "test 5", "type": "alien"}
]

how would I get the length of friends where pending would be excluded? I'm using this, but is there an easier way?

let total = friends.filter(friend=>friend.type==='friends').length + friends.filter(friend=>friend.type==='alien').length;

Ele · Accepted Answer · 2018-03-13T23:23:02.397

2

You don't need to filter that array to create a new array and then get its length, just use the function reduce to make a simple count.

let friends = [    {"name": "test 1", "type": "pending"},     {"name": "test 2", "type": "friends"},     {"name": "test 3", "type": "friends"},    {"name": "test 4", "type": "friends"},    {"name": "test 5", "type": "alien"}],
    count = friends.reduce((a, t) => a + (t.type !== 'pending'), 0);

console.log(count);

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edited Mar 13 '18 at 23:23

answered Mar 13 '18 at 22:08

Ele

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No need for a conditional, `a + (t.type !== 'pending')` should do it. – georg Mar 13 '18 at 22:50
@georg come on!! `:)` good advice! – Ele Mar 13 '18 at 23:23

Sajeetharan · Answer 2 · 2018-03-13T22:02:37.173

1

You can directly do with single filter query with !=

DEMO

let friends = [
    {"name": "test 1", "type": "pending"}, 
    {"name": "test 2", "type": "friends"}, 
    {"name": "test 3", "type": "friends"},
    {"name": "test 4", "type": "friends"},
    {"name": "test 5", "type": "alien"}
];

let count = friends.filter(t=>t.type !== 'pending').length;

console.log(count);

edited Mar 13 '18 at 22:02

answered Mar 13 '18 at 21:59

Sajeetharan

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OP used `===` so I think your answer should use `!==` instead of `!=`. – T Tse Mar 13 '18 at 22:02
@ShioT Yes updated – Sajeetharan Mar 13 '18 at 22:02

get length of json array of objects that match a specific string

2 Answers2