How to create an array from an array of objects

Question

Given the following:

var example = [{
  "logged": {
    "status": 0,
    "status_name": "Logged",
    "hours": 23 // to the hours array
  },
  "pending": {
    "status": 3,
    "status_name": "Pending",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 6, // to the hours array
      "count": 1
    }
  },
  "denied": {
    "status": 4,
    "status_name": "Denied",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  },
  "approved": {
    "status": 2,
    "status_name": "Approved",
    "contribution": {
      "hours": 4.5,
      "count": 1
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  }
}];

How would I construct two (2) arrays like such:

var statusNames = ["Logged", "Pending", "Denied", "Approved"];
var hours = [23, 6, 0, 0];

I can infer how to get the rest if the values from the solution.

So, you want one array that has all the keys, and another that has all values for a particular key - one which can be arbitrarily nested - is that correct? — VLAZ
– VLAZ, Commented Sep 20, 2016 at 16:48
No simple way I guess, you will need to loop through each of those elements and add it to the array — Pritam Banerjee
– Pritam Banerjee, Commented Sep 20, 2016 at 16:54
Just a conventional use case for Array#map... What efforts did you put ? — Rayon
– Rayon, Commented Sep 20, 2016 at 16:55
@PritamBanerjee I don't think it's that hard. It seems to me that the first task is trivial, the second is merely easy. There are already built in ways to interact in an array to produce these results. — VLAZ
– VLAZ, Commented Sep 20, 2016 at 16:56

Nina Scholz · Accepted Answer · 2016-09-20 16:59:31Z

You could iterate over the array and over the keys, check if the property exist and include the wanted part into the arrays.

var example = [{ "logged": { "status": 0, "status_name": "Logged", "hours": 23 }, "pending": { "status": 3, "status_name": "Pending", "contribution": { "hours": 0, "count": 0 }, "verification": { "hours": 6, "count": 1 } }, "denied": { "status": 4, "status_name": "Denied", "contribution": { "hours": 0, "count": 0 }, "verification": { "hours": 0, "count": 0 } }, "approved": { "status": 2, "status_name": "Approved", "contribution": { "hours": 4.5, "count": 1 }, "verification": { "hours": 0, "count": 0 } } }],
    statusNames = [],
    hours = [];

example.forEach(function (o) {
    Object.keys(o).forEach(function (k) {
        if ('hours' in o[k]) {
            statusNames.push(k);
            hours.push(o[k].hours);
            return;
        }
        if ('verification' in o[k]) {
            statusNames.push(k);
            hours.push(o[k].verification.hours);
        }
    });
});
console.log(statusNames);
console.log(hours);

Pranav C Balan · Accepted Answer · 2016-09-20 17:13:07Z

Use Object.keys method for getting all object property name array and then generate the result arrays using Array#map method.

// array for storing the hours value
var hours = [];
// genarte the statusName array
var statusNames = Object.keys(example[0]) // get object keys
            // iterate over key value          
            .map(function(k) {
                // get the value of hour and push it to hours array
                // get `hours` property if defined or get hours property
                // of nested object verification or push 0
                hours.push(example[0][k].hours || example[0][k].verification.hours || 0); 
                // get the status name and return
                return example[0][k].status_name;
            })

var example = [{
  "logged": {
    "status": 0,
    "status_name": "Logged",
    "hours": 23 // to the hours array
  },
  "pending": {
    "status": 3,
    "status_name": "Pending",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 6, // to the hours array
      "count": 1
    }
  },
  "denied": {
    "status": 4,
    "status_name": "Denied",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  },
  "approved": {
    "status": 2,
    "status_name": "Approved",
    "contribution": {
      "hours": 4.5,
      "count": 1
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  }
}];

var hours = [];
var statusNames = Object.keys(example[0]).map(function(k) {
  hours.push(example[0][k].hours || example[0][k].verification.hours || 0);
  return example[0][k].status_name;
})

console.log(hours, statusNames)

n1ru4l · Accepted Answer · 2016-09-20 16:59:18Z

You would have to use Array.prototype.reduce to filter the information you need.

var example = [{
  "logged": {
    "status": 0,
    "status_name": "Logged",
    "hours": 23 // to the hours array
  },
  "pending": {
    "status": 3,
    "status_name": "Pending",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 6, // to the hours array
      "count": 1
    }
  },
  "denied": {
    "status": 4,
    "status_name": "Denied",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  },
  "approved": {
    "status": 2,
    "status_name": "Approved",
    "contribution": {
      "hours": 4.5,
      "count": 1
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  }
}]

var statusNames = example.reduce(function(prevVal, currVal) {
  for(var key in currVal) {
    if(!Object.prototype.hasOwnProperty.call(currVal, key)) continue

    if(currVal[key].status_name) {
      prevVal.push(currVal[key].status_name)
    }
   
  }
  return prevVal
}, [])


console.log(statusNames)

andre mcgruder · Accepted Answer · 2016-09-20 17:00:08Z

0

This should work.

// get all of the objects keys
var statusNames = Object.keys(example);
var hours = [];

// get all of the hours
example.forEach( function(item, idx){
    idx === 0 ? hours.push(item.hours) : false; // because the hours in your first object is not nested.
    idx > 0 ? hours.push(item.verification.hours) : false; // gets all of the nested hours.
});

answered Sep 20, 2016 at 17:00

andre mcgruder

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Comments

Md Sifatul Islam · Accepted Answer · 2016-09-20 17:38:13Z

use for (var key in example[0]) for iteration through each key.

Then push the values in respective arrays

statusNames.push(key); hours.push(example[0][key]["hours"] || example[0][key]["verification"]["hours"] );

var  statusNames = [];
   var hours = [];
   
var example = [{
  "logged": {
    "status": 0,
    "status_name": "Logged",
    "hours": 23 // to the hours array
  },
  "pending": {
    "status": 3,
    "status_name": "Pending",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 6, // to the hours array
      "count": 1
    }
  },
  "denied": {
    "status": 4,
    "status_name": "Denied",
    "contribution": {
      "hours": 0,
      "count": 0
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  },
  "approved": {
    "status": 2,
    "status_name": "Approved",
    "contribution": {
      "hours": 4.5,
      "count": 1
    },
    "verification": {
      "hours": 0, // to the hours array
      "count": 0
    }
  }
}];


for (var key in example[0]) {
      statusNames.push(key);
			hours.push(example[0][key]["hours"] || example[0][key]["verification"]["hours"] );
     
}
console.log(statusNames);
console.log(hours);

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