Map 特定属性从一个数组变成一个新数组

Question

I have the following array of employees. I want to create a new array employeeNames that has only the firstName and lastName properties. I believe I can do this with the map() method but I'm not exactly sure how.

let employees = { firstName: 'Collin', lastName: 'Sexton', email: 'exampe@test.com', dob: '03/20/1986' ... }

Resulting array should look like:

employeeNames = { firstName: 'Collin', lastName: 'Sexton' }

Answer 1

You are not looking for array as a result though.. do this

let { firstName, lastName } = employees;
let employeeNames = { firstName, lastName };

What we do here is called deconstruction. We bind the values of 'firstName' and 'lastName' to variables with the same name and then create a new Object with those variables. If no keys are given, it automagically names them after the variables.

Answer 2

employees is an object which is not iterable, so you need to convert before being able to map() a new one.

Which can easity be made with Object.entries()

so..

// key is the object key while value is the object value of corresponding key
let newArray = Object.entries(employees).map((key, value) => {
   let arrayEntry;
   if (key === 'firstName' || key === 'lastName') {
      newEntry = value;
   }
   return arrayEntry;
});

Your new array should then output to [John, Doe, Jane, Doe, name, lastname]

Answer 3

Probably you meant you have array of objects. So you'd do:

const projected = empArray.map((empItem) => ({
    firstName: empItem.firstName,
    lastName: empItem.lastName,
}));

Answer 4

Here is how it will be if you need to map array of eployees to array with only needed props:

let employees = [{ firstName: 'Collin', lastName: 'Sexton', email: 'exampe@test.com', dob: '03/20/1986'}]
let result = employees.map({firstName, lastName}=> ({ firstName, lastName}));