Filter an object based on values in an array-CodePudding

I have an object that contains people's names and ages

{"John":44,"Sarah":23,"Bob":43,"Kate":65,"Bill":18}

and an array that provides a list of employee names

['John', 'Bob', 'Kate', 'Bill', 'Fred']

I would like to create a new object which contains only those people and their ages that appear in both the object and array. So in this example the new object would contain

{"John":44,"Bob":43,"Kate":65,"Bill":18}

"Sarah":23 and Fred don't appear because they appear in only one of the above.

Can anyone advise on how to do this please?

CodePudding user response：

You can use reduce to create the result and operator in to check if the key exists:

const obj = {"John":44,"Sarah":23,"Bob":43,"Kate":65,"Bill":18};
const keys = ['John', 'Bob', 'Kate', 'Bill', 'Fred'];

const result = keys.reduce((acc, el) => {
  if (el in obj) acc[el] = obj[el];
  return acc;
}, {});

console.log(result);

Another approach is to convert the object to an array, use filter and convert the result back:

const obj = {"John":44,"Sarah":23,"Bob":43,"Kate":65,"Bill":18};
const keys = ['John', 'Bob', 'Kate', 'Bill', 'Fred'];

const result = Object.fromEntries(Object.entries(obj).filter(([key]) => keys.includes(key)));

console.log(result);

CodePudding user response：

simply

const 
  jso = { John: 44, Sarah: 23, Bob: 43, Kate: 65, Bill: 18 } 
, arr = [ 'John', 'Bob', 'Kate', 'Bill', 'Fred' ]
, res = arr.reduce((r,a)=>(!!jso[a]?r[a]=jso[a]:'',r),{})
  ;
console.log(res)