javascript map function returning-CodePudding

I need to assign idNumber of all participants to idNumbers. Can you please check my code?

const participants = [
  { name: 'Abu', idNumber: 'S7282395H', gender: 'male' },
  { name: 'Mary', idNumber: 'T4689018Z', gender: 'female' },
  { name: 'Suzi', idNumber: 'G5512873T', gender: 'female' },
  { name: 'T Chakra', idNumber: 'T8198514B', gender: 'male' }
];
// pass a function to map
const getIds= participants.map((name) => `${participants.name} ${participants.idNumber}`);
console.log(getIds);

CodePudding user response：

You should be referencing name and not participants inside the map:

const participants = [
  { name: 'Abu', idNumber: 'S7282395H', gender: 'male' },
  { name: 'Mary', idNumber: 'T4689018Z', gender: 'female' },
  { name: 'Suzi', idNumber: 'G5512873T', gender: 'female' },
  { name: 'T Chakra', idNumber: 'T8198514B', gender: 'male' }
];
// pass a function to map
const getIds= participants.map((name) => `${name.name} ${name.idNumber}`);
console.log(getIds);

CodePudding user response：

In this piece of code

const getIds= participants.map((name) => `${participants.name} ${participants.idNumber}`);

you need to reference the name argument, not participants. That needs to be

const getIds= participants.map((name) => `${name.name} ${name.idNumber}`);

I recommend changing the name parameter to something more distinct, since name.name is not really clean, per se...

CodePudding user response：

If you just want an array of idNumber then you can use map like this

const participants = [
{ name: 'Abu', idNumber: 'S7282395H', gender: 'male' },
{ name: 'Mary', idNumber: 'T4689018Z', gender: 'female' },
{ name: 'Suzi', idNumber: 'G5512873T', gender: 'female' },
{ name: 'T Chakra', idNumber: 'T8198514B', gender: 'male' }];

const getIds = participants.map(participant =>  participant.idNumber);

console.log(getIds);

If you want an array of strings containing the name and the idNumber you can use string interpolation for that.

const participants = [
{ name: 'Abu', idNumber: 'S7282395H', gender: 'male' },
{ name: 'Mary', idNumber: 'T4689018Z', gender: 'female' },
{ name: 'Suzi', idNumber: 'G5512873T', gender: 'female' },
{ name: 'T Chakra', idNumber: 'T8198514B', gender: 'male' }];

const getIds = participants.map(participant =>  `${participant.name} ${participant.idNumber}`);

console.log(getIds);

CodePudding user response：

Hmm I'm not sure if this is exactly what you want, but it sounds like you want to get an array of all participant idNumber values. In that case, perhaps something like this?

const idNumbers = participants.map((participant) => participant.idNumber));

In your code inside the map callback, you're currently trying to access name and idNumber from participants, which will return undefined since participants is an array and doesn't have those props. What you want to do is access these props in each individual participant from the callback argument.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map