How to loop through an array of object, push keys to another array

Question

I have the following array, I want to loop through it and push the key values to another declared array. Then, loop through the array and push field and values of a key to another array.

timeframe = [];

timeframeValueKeyUSD = [];

timeframeValueKeyCAD = [];

array = [
       {
      "2012-05-01":{
        "USD": 1.322891,
        "AUD": 1.278047,
        "CAD": 1.302303
      },
      "2012-05-02": {
        "USD": 1.315066,
        "AUD": 1.274202,
        "CAD": 1.299083
      },
      "2012-05-03": {
        "USD": 1.314491,
        "AUD": 1.280135,
        "CAD": 1.296868
      }
  }
]

I want to get the arrays as this:

timeframe = ['2012-05-01', '2012-05-02', '2012-05-03'];

timeframeValueKeyUSD = [1.315066, 1.315066, 1.314491];

timeframeValueKeyCAD = [1.302303, 1.299083, 1.296868];

use maps. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Naramsim
– Naramsim, Commented Jun 13, 2018 at 6:40

Nina Scholz · Accepted Answer · 2018-06-13 07:02:25Z

2

You could get the dates first and then map the values according to the dates.

function getKeys(o) {
    return Object.keys(o);
}

function getValueBy(object, groups, key) {
    return groups.map(k => object[k][key]);
}

var array = [{ "2012-05-01":{ USD: 1.322891, AUD: 1.278047, CAD: 1.302303 }, "2012-05-02": { USD: 1.315066, AUD: 1.274202, CAD: 1.299083 }, "2012-05-03": { USD: 1.314491, AUD: 1.280135, CAD: 1.296868 } }],
    timeframe = getKeys(array[0]);
    timeframeValueKeyUSD = getValueBy(array[0], timeframe, 'USD'),
    timeframeValueKeyCAD = getValueBy(array[0], timeframe, 'CAD');

console.log(timeframe);
console.log(timeframeValueKeyUSD);
console.log(timeframeValueKeyCAD);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Jun 13, 2018 at 7:02

Nina Scholz

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Comments

Ankit Agarwal · Accepted Answer · 2018-06-13 06:46:51Z

Use a simple forEach() loop to get the desired output.

timeframe = [];

var timeframeValueKeyUSD = [];

var timeframeValueKeyCAD = [];

var array = [
       {
      "2012-05-01":{
        "USD": 1.322891,
        "AUD": 1.278047,
        "CAD": 1.302303
      },
      "2012-05-02": {
        "USD": 1.315066,
        "AUD": 1.274202,
        "CAD": 1.299083
      },
      "2012-05-03": {
        "USD": 1.314491,
        "AUD": 1.280135,
        "CAD": 1.296868
      }
  }
]

array.forEach((obj)=>{
  var keys = Object.keys(obj);
  timeframe.push(...keys);
  keys.forEach((key)=>{
     timeframeValueKeyUSD.push(obj[key].USD);
     timeframeValueKeyCAD.push(obj[key].CAD);
  });
});

console.log(timeframe);
console.log(timeframeValueKeyUSD);
console.log(timeframeValueKeyCAD);

score 1 · Accepted Answer · 2018-06-13 08:34:46Z

1

You can use for loop to traverse :

var timeframe = [];
var timeframeValueKeyUSD = [];
var timeframeValueKeyCAD = [];
var array = [{"2012-05-01":{"USD":1.322891,"AUD":1.278047,"CAD":1.302303},"2012-05-02":{"USD":1.315066,"AUD":1.274202,"CAD":1.299083},"2012-05-03":{"USD":1.314491,"AUD":1.280135,"CAD":1.296868}}];
for (var t in array[0]) {
  timeframe.push(t);
  timeframeValueKeyUSD.push(array[0][t].USD);
  timeframeValueKeyCAD.push(array[0][t].CAD);
}
console.log(timeframe, timeframeValueKeyUSD, timeframeValueKeyCAD);

edited Jun 13, 2018 at 8:34

answered Jun 13, 2018 at 6:49

user2575725

Comments

Leonid Pyrlia · Accepted Answer · 2018-06-13 08:54:18Z

A shorter ES6 declarative alternative:

const dataObj = array[0];
const { timeframe, timeframeValueKeyUSD, timeframeValueKeyCAD } = Object.keys(dataObj).reduce((all, timeframe) => {

    const { USD, CAD } = dataObj[timeframe];

    all.timeframe.push(timeframe);
    all.timeframeValueKeyUSD.push(USD);
    all.timeframeValueKeyCAD.push(CAD);

    return all;

}, {timeframe: [], timeframeValueKeyUSD: [], timeframeValueKeyCAD: []});

console.log(timeframe);
console.log(timeframeValueKeyUSD);
console.log(timeframeValueKeyCAD);

If you want to make it even more dynamic (to cover all possible currencies):

const dataObj = array[0];
const result = Object.keys(dataObj).reduce((all, timeframe) => {

    const currencies = Object.keys(dataObj[timeframe]);

    all.timeframe.push(timeframe);

    currencies.forEach(currency => {

        if (!all.hasOwnProperty(`timeframeValueKey${currency}`)) {
            all[`timeframeValueKey${currency}`] = [];
        }

        all[`timeframeValueKey${currency}`].push(dataObj[timeframe][currency]);

    });

    return all;

}, {timeframe: [] });


console.log(result);

timeframe:(3) ["2012-05-01", "2012-05-02", "2012-05-03"]
timeframeValueKeyAUD:(3) [1.278047, 1.274202, 1.280135]
timeframeValueKeyCAD:(3) [1.302303, 1.299083, 1.296868]
timeframeValueKeyUSD:(3) [1.322891, 1.315066, 1.314491]

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