CODEWITHSUNDEEP
javascriptarrays
BellamyGray
BellamyGray

Reputation: 45

Array of Arrays to Array of Objects JS

This particular challenge calls for me to convert an array of arrays (is there a term for this?) into an array of objects, like so:

[[['firstName', 'Joe'], ['lastName', 'Blow'], ['age', 42], ['role', 'clerk']],
[['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['role', 'manager']]]

into:

[{firstName: 'Joe', lastName: 'Blow', age: 42, role: 'clerk'},
{firstName: 'Mary', lastName: 'Jenkins', age: 36, role: 'manager'}]

Here's my code, so far:

function transformEmployeeData(array) {
var object={};
for (var i = 0; i < array.length;i++){
    var newArray = array[i];
    object[i] = newArray[1];
    object[newArray[0]] = object[i];
    newArray.push(object);
    delete object[i];
    }
return object;
}

var myArray= [['firstName','Joe'],['lastName','Blow'],['age', 42], ['role','clerk']];
transformEmployeeData(myArray);

It seems to work great, until I add another nested array with a second (or third, or fourth, which is the whole point of the thing) employee's data.

I'm sure it has something to do with the loop, but I can't spot it.

Help appreciated!

Upvotes: 3

Views: 11397

Answers (4)

JeanJacquesGourdin
JeanJacquesGourdin

Reputation: 1853

With Object.fromEntries, a one liner

let input = [[['firstName', 'Joe'], ['lastName', 'Blow'], ['age', 42], ['role', 'clerk']],
[['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['role', 'manager']]]

console.log(input.map(elem => Object.fromEntries(elem)))

Upvotes: 0

Pabhoz
Pabhoz

Reputation: 86

Here's my solution using forEach Array object method

    var array = [[['firstName', 'Joe'], ['lastName', 'Blow'], ['age', 42], ['role', 'clerk']],
    [['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['role', 'manager']]];

    transformEmployeeData(array);

    function transformEmployeeData(array){
      var employees = [];
      array.forEach(function(employee,index){
        var employeeObj = {};
        employee.forEach(function(data,key){
          employeeObj[data[0]] = data[1];
        });
        employees.push(employeeObj);
      });
      return employees;
    }

Upvotes: 1

nnnnnn
nnnnnn

Reputation: 150080

You need to create a new object inside the loop, so that you're creating a new object each time rather than just reassigning properties of the same object - you were pushing the same object into the array multiple times. (I'm not sure why you were using delete - you don't need it.)

So something like this:

function transformEmployeeData(data) {
  var result = []                              // new array to hold transformed data
  var key, value
  for (var i = 0; i < data.length; i++) {      // loop over employees
    var employee = {}                          // new object for current employee
    for (var j = 0; j < data[i].length; j++) { // loop over current employee details
      key = data[i][j][0]                      // extract property key name
      value = data[i][j][1]                    // and value
      employee[key] = value                    // add property to object
    }
    result.push(employee)                      // add new object to array
  }
  return result
}

var input = [[['firstName', 'Joe'], ['lastName', 'Blow'], ['age', 42], ['role', 'clerk']],
[['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['role', 'manager']]]

console.log( transformEmployeeData(input) )

Or if you want to use some array functions like .map() and .reduce() you can "simplify" the code:

function transformEmployeeData(data) {
  return data.map(function(employee) {
    return employee.reduce(function(a, c) {
      a[c[0]] = c[1]
      return a
    }, {})
  })
}

var input = [[['firstName', 'Joe'], ['lastName', 'Blow'], ['age', 42], ['role', 'clerk']],
[['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['role', 'manager']]]

console.log( transformEmployeeData(input) )

Upvotes: 4

Robby Cornelissen
Robby Cornelissen

Reputation: 97381

Here's a solution using Array.prototype.map() and Array.prototype.reduce():

let arrayOfArrays = [[['firstName', 'Joe'], ['lastName', 'Blow'], ['age', 42], ['role', 'clerk']],
[['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['role', 'manager']]];

let arrayOfObjects = arrayOfArrays.map(array => array.reduce((acc, val) => {
  acc[val[0]] = val[1];
  return acc;
}, {}));

console.log(arrayOfObjects);

Upvotes: 3

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