return an array containing the value associated with that key for each object

Question

As the title states, I am trying to return an array containing the value associated with that key for each object, or undefined if that key is not present.

Here is what I have so far:

function pluck(arr, name) {

permittedValues = arr.map(function(value) {
  return value.key || undefined;
});
}
console.log(
  pluck([
  { name: "Tim" }, { name: "Matt" }, { name: "Elie" }],
 'name'
)
  );

I am trying to return something like this:

// ["Tim", "Matt", "Elie"]

`value.key` is the property named `key`, **not** the property named whatever the *value* of `key` is. See e.g. https://stackoverflow.com/q/4841254/3001761. — jonrsharpe, Dec 30 '19 at 18:26
You have no variable named `key`. Did you mean to write `function pluck(arr, key)`? — Barmar, Dec 30 '19 at 18:30

Shahzad · Answer 1 · 2019-12-30T18:27:40.353

2

You can use indexer to get the property and if it doesn't exist, undefined will be returned:

function pluck(arr, name) {
    return arr.map(function (value) {
        return value[name];
    });
}

edited Dec 30 '19 at 18:27

answered Dec 30 '19 at 18:25

Shahzad

2,033
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kooskoos · Answer 2 · 2019-12-30T18:33:31.390

You don't need to return value[name] || undefined, if name key doesn't exist it will return undefined anyway.

function pluck(arr, name) {

return permittedValues = arr.map(value => 
  value[name]);
}
console.log(
  pluck([
  { name: "Tim" }, { name: "Matt" }, { name: "Elie" }],
 'name'
)
  );

This code can get even more concise using arrow functions

const pluck = (arr, name) => arr.map(value => value[name])

console.log(pluck([{ name: "Tim" }, { name: "Matt" }, { name: "Elie" }],'name'));

return an array containing the value associated with that key for each object

2 Answers2