How to output keys in key value pairs in nested arrays JavaScript

Admin 1
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Inside the array of item, there's an array with with the name 'folder'and inside the array there's 'info' How can I be able to print only the keys and not the value from the info array? as in print out 'created' and 'modified" ?

let item = [
  {
    itemName: 'folder',
    info:
    {
      created:'August 13 2013',
      modified: 'December 06 2017'
    }
  },
  {
    itemName: 'new folder',
    info: 'ruby files'
  },
  {
    itemName: 'documents',
    info: ''  
  }
]

key-value key arrays javascript
4 Answers

You can print the object keys by looping the array and use Object.keys() to print the keys

user_35274650

Check each item with forEach and if an item's info property is an object, print its keys.

item.forEach(data => {
  if(data.info.constructor === Object) {
    console.log(Object.keys(data.info));
  }
})
user_96071050

look at each property and use a recursing function to go deeper :

  let item = [
  {
    itemName: 'folder',
    info:
    {
      created:'August 13 2013',
      modified: 'December 06 2017'
    }
  },
  {
    itemName: 'new folder',
    info: 'ruby files'
  },
  {
    itemName: 'documents',
    info: ''  
  }
];

var console=window.console;

function displayObj(obj) {
    if (obj instanceof Array) {
        for (var i = 0; i < obj.length; i++) {
            console.log('obj['+i+']='+obj[i]);
            displayObj(obj[i]);
        }

    }
    if (obj instanceof Object) {
        for (var p in obj) {
            console.log('obj.'+p+'='+obj[p]);
            displayObj(obj[p]);
        }
    }
}

displayObj(item);
user_27030580

Well, it's not infinitely recursive, but it works (i'll try to ameliorate it)

let items = [
    {
        itemName: 'folder',
        info:
        {
            created:'August 13 2013',
            modified: 'December 06 2017'
        }
    },
    {
        itemName: 'new folder',
        info: 'ruby files'
    },
    {
        itemName: 'documents',
        info: ''    
    }
];

let Keys = [];

items.forEach((el, index) => {
    Object.keys(el).forEach(key => {
        if(!Keys[index])
            Keys[index] = [];
        if(typeof el[key] === 'object'){
            Keys[index].push(Object.keys(el[key]));
        }
        else {
            Keys[index].push(key);
        }
    })
});

JSFiddle

user_84589650
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