CODEWITHSUNDEEP
javascriptnode.js
Scrat Sober
Scrat Sober

Reputation: 55

How to filter the map only equal to the items in the array

hello guys i have a map like this

Map {
'708335088638754946' => 38772,
'712747381346795670' => 12051,
'712747409108762694' => 12792 
}

and i have a array like 

let array = ["712747381346795670", "708335088638754946"]

How can I filter the map only equal to the items in the array

Upvotes: 1

Views: 58

Answers (4)

Ele
Ele

Reputation: 33726

You can use the function Object.entries along with the function Array.prototype.map as follow:

let data = {'708335088638754946': 38772,'712747381346795670': 12051,'712747409108762694': 12792 };
let array = ["712747381346795670", "708335088638754946"];
let result = Object.entries(data)
      .filter(([k]) => array.includes(k))
      .map(([key,value]) => ({[key]: value}));
      
console.log(result);

Another approach could be the function Array.prototype.reduce

let data = {'708335088638754946': 38772,'712747381346795670': 12051,'712747409108762694': 12792 };
let array = ["712747381346795670", "708335088638754946"];
let result = Object.entries(data)
      .reduce((a, [k, v]) => a.concat(array.includes(k) ? {[k]: v} : []), []);
      
console.log(result);

Using the object Map

let data = new Map([['708335088638754946', 38772],['712747381346795670', 12051], ['712747409108762694', 12792]]);
let array = ["712747381346795670", "708335088638754946"];

let result = new Map(Array.from(data.keys())
      .reduce((a, k) => a.concat(array.includes(k) ? [[k, data.get(k)]] : []), []));

console.log(result.has("712747409108762694"));
console.log(result.has("708335088638754946"));
console.log(result.has("712747381346795670"));

Upvotes: 1

Michal Szorád
Michal Szorád

Reputation: 215

const oldMap = new Map([["a", "1"], ["b", "2"], ["c", "3"]]);
const array = ["a", "c"];
const newMap = new Map(array.map(key => [key, oldMap.get(key)]));

// newMap is the same as oldMap but only with keys from array

or

const oldMap = new Map([["a", "1"], ["b", "2"], ["c", "3"]]);
const array = ["a", "c"];
const newMap = new Map([...oldMap.entries()].filter(entry => array.includes(entry[0])))

// newMap is the same as oldMap but only with keys from array

Upvotes: 1

fengxh
fengxh

Reputation: 384

const map = new Map([["a", "b"], ["c", "d"], ["e", "f"]]);
const array = ["a", "c"];
console.log(map);
for (let [prop, value] of map) {
  if (array.includes(prop)) {
    // collect matched items here
  }
}

Upvotes: 1

Sirko
Sirko

Reputation: 74036

You could just iterate over all entries and only add matching entries to the result:

const result = new Map();
const array = ["712747381346795670", "708335088638754946"];
for( const [ key, value ] of input.entries() ) {
  if( array.includes( key ) ) {
    result.set( key, value );
  }
}

Upvotes: 1

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