Map returns [Array(3)] instead of proper Array-CodePudding

In my app, I need an array of diagnosis codes in the form of ['Z57.1', 'Z74.3', 'M51.2'] so I can have access to each of them.

However, when mapping through diagnosis codes, I get [Array(3)] in the console instead of ['Z57.1', 'Z74.3', 'M51.2'], meaning I can't get access to the codes.

How do you map through patient.entries to return ['Z57.1', 'Z74.3', 'M51.2'] in the console instead of [Array(3)]?

 const patient =  {
          id: 'd2773598-f723-11e9-8f0b-362b9e155667',
          name: 'Martin Riggs',
          dateOfBirth: '1979-01-30',
          ssn: '300179-777A',
          gender: Gender.male,
          occupation: 'Cop',
          entries: [
            {
              id: 'fcd59fa6-c4b4-4fec-ac4d-df4fe1f85f62',
              date: '2019-08-05',
              type: 'OccupationalHealthcare',
              specialist: 'MD House',
              employerName: 'HyPD',
              diagnosisCodes: ['Z57.1', 'Z74.3', 'M51.2'],
              description:
                'Patient mistakenly found himself in a nuclear plant waste site without protection gear. Very minor radiation poisoning. ',
              sickLeave: {
                startDate: '2019-08-05',
                endDate: '2019-08-28',
              },
            },
          ],
        },
const codes = patient?.entries.map(c => c.diagnosisCodes);

const codes returns:

[Array(3)]
0
: 
(3) ['Z57.1', 'Z74.3', 'M51.2']
length
: 
1
[[Prototype]]
: 
Array(0)

CodePudding user response：

You could use Array.prototype.flatMap.

It works like map, but flattens nested arrays into a single monolithic array.

Your main issue is that you have n-number of entries with m-number of diagnosis codes. Your resulting array of codes will be 2-dimensional. Flattening the matrix will result in a linear array.

const main = () => {
  const codes = patient.entries.flatMap(c => c.diagnosisCodes);
  console.log(codes);
};

const Gender = { male: 'Male', female: 'Female', other: 'Other' };

const patient = {
  id: 'd2773598-f723-11e9-8f0b-362b9e155667',
  name: 'Martin Riggs',
  dateOfBirth: '1979-01-30',
  ssn: '300179-777A',
  gender: Gender.male,
  occupation: 'Cop',
  entries: [{
    id: 'fcd59fa6-c4b4-4fec-ac4d-df4fe1f85f62',
    date: '2019-08-05',
    type: 'OccupationalHealthcare',
    specialist: 'MD House',
    employerName: 'HyPD',
    diagnosisCodes: ['Z57.1', 'Z74.3', 'M51.2'],
    description: 'Patient mistakenly found himself in a nuclear plant waste site without protection gear. Very minor radiation poisoning. ',
    sickLeave: {
      startDate: '2019-08-05',
      endDate: '2019-08-28',
    }
  }]
};

main();

CodePudding user response：

const patient = {
          id: 'd2773598-f723-11e9-8f0b-362b9e155667',
          name: 'Martin Riggs',
          dateOfBirth: '1979-01-30',
          ssn: '300179-777A',
          //gender: Gender.male,
          occupation: 'Cop',
          entries: [
            {
              id: 'fcd59fa6-c4b4-4fec-ac4d-df4fe1f85f62',
              date: '2019-08-05',
              type: 'OccupationalHealthcare',
              specialist: 'MD House',
              employerName: 'HyPD',
              diagnosisCodes: ['Z57.1', 'Z74.3', 'M51.2'],
              description:
                'Patient mistakenly found himself in a nuclear plant waste site without protection gear. Very minor radiation poisoning. ',
              sickLeave: {
                startDate: '2019-08-05',
                endDate: '2019-08-28'
              }
            }
          ]
        };
        
const codes = patient.entries.reduce((t, v) => [...t, ...v.diagnosisCodes], []);
console.log(codes);