Re-arranging An Array To Have Keys Have Values

I have a Javascript array of objects as below const lab = [ { name: 'Lance', item: 'PS', '3-Aug-21': '117.69', '4-Aug-21': '120.1', '5-Aug-21': '122.08', },

Solution 1:

Using destructuring to isolate and rename the properties we're interested in at each level of refactoring.

const lab = [{ name: "Lance", item: "PS", "3-Aug-21": "117.69", "4-Aug-21": "120.1", "5-Aug-21": "122.08", }, { name: "Sam", item: "PS", "3-Aug-21": "100.14", "4-Aug-21": "101.2", "5-Aug-21": "103", }, { name: "Vince", item: "PS", "3-Aug-21": "12.65", "4-Aug-21": "13.29", "5-Aug-21": "13.68", },];

const labCheck = lab.map(({ name: id, item, ...values }) => ({
  id,
  values: Object.entries(values).map(([date, risklevel]) => ({ date, risklevel }))
}));

console.log(labCheck)

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If you need to mutate values as part of the refactoring you can't use the property shorthand but will need to explicitly declare each property and assign the relevant mutated value.

const lab = [{ name: "Lance", item: "PS", "3-Aug-21": "117.69", "4-Aug-21": "120.1", "5-Aug-21": "122.08", }, { name: "Sam", item: "PS", "3-Aug-21": "100.14", "4-Aug-21": "101.2", "5-Aug-21": "103", }, { name: "Vince", item: "PS", "3-Aug-21": "12.65", "4-Aug-21": "13.29", "5-Aug-21": "13.68", },];

const labCheck = lab.map(({ name: id, item, ...values }) => ({
  id,
  values: Object.entries(values).map(([date, risklevel]) => ({ 
    date: new Date(Date.parse(date)), // Date.parse() is not reliable, but used as example here.
    risklevel: +risklevel 
  }))
}));

console.log(labCheck)

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Solution 2:

The problem is here:

Object.keys(lab[0])

You ALWAYS take the first element of the array, instead of iteration over themn.

Also, you concatenate two .map method. When you do that, the second map will receive as input the output of the previous method, in your case the name, thus losing access to the original element.

You can use:

const lab=[{name:"Lance",item:"PS","3-Aug-21":"117.69","4-Aug-21":"120.1","5-Aug-21":"122.08"},{name:"Sam",item:"PS","3-Aug-21":"100.14","4-Aug-21":"101.2","5-Aug-21":"103"},{name:"Vince",item:"PS","3-Aug-21":"12.65","4-Aug-21":"13.29","5-Aug-21":"13.68"}];


const labCheck = lab.map((item) => {
  return {
    id: item.name,
    values: Object.keys(item)
      // The order of the keys is not guaranteed, better not to use .slice() because it could fail on unpredicatable situations
      .filter((key) => key !== 'name' && key !== 'item')
      .map((key) => {
        return { date: key, riskLevel: item[key] }
      })
  }
})

console.log(labCheck)

Solution 3:

You can do something like this :

const lab = [
  {
    name: "Lance",
    item: "PS",
    "3-Aug-21": "117.69",
    "4-Aug-21": "120.1",
    "5-Aug-21": "122.08",
  },
  {
    name: "Sam",
    item: "PS",
    "3-Aug-21": "100.14",
    "4-Aug-21": "101.2",
    "5-Aug-21": "103",
  },
  {
    name: "Vince",
    item: "PS",
    "3-Aug-21": "12.65",
    "4-Aug-21": "13.29",
    "5-Aug-21": "13.68",
  },
];

const formattedLab = lab.map((el) => {
  const values = Object.entries(el).slice(2);
  return {
    id: el.name,
    values: values.map(value => ({
      date: value[0],
      riskLevel: +value[1]
    })),
  }
});

console.log(formattedLab);

Solution 4:

map over the Object.entries to access the data in the array and return it.

const lab=[{name:"Lance",item:"PS","3-Aug-21":"117.69","4-Aug-21":"120.1","5-Aug-21":"122.08"},{name:"Sam",item:"PS","3-Aug-21":"100.14","4-Aug-21":"101.2","5-Aug-21":"103"},{name:"Vince",item:"PS","3-Aug-21":"12.65","4-Aug-21":"13.29","5-Aug-21":"13.68"}];

// `map` over the array
const out = lab.map(obj => {

  // Grab the name, and item, and then everything else
  const { name, item, ...rest } = obj;

  // `map` over the object entries and for each iteration
  // return a new object
  const values = Object.entries(rest).map(([key, value]) => {
    return { date: key, riskLevel: value };
  });

  // Return the new array
  return { name, values };

});

console.log(out);

Solution 5:

This works for me:

const labCheck = lab.map((obj, i) => {
    const newObj = {id: obj.name, values: []};
    Object.keys(lab[i]).slice(2).forEach(date => {
        newObj.values.push({
            date: date, 
            risklevel: lab[i][date]
        });
    })
    return newObj;
})