How to parse/filter data from JSON file in Javascript

Question

Is there any way to parse/filter the data present in JSON file in a Javascript file.

Basically, I am calling JSON file into my local javascript. I am having trouble in reading specific data and printing.

Can anyone please help.

JSON file contains:

{
    "Data": [
    {

    "name": "John",
    "age": 30
    },

    {
    "joined on":"Jan 2015",
    "working on": "Automation",
    }
]
}

I am trying to read the above JSON file as:

var jfile = require("./Example.json");

var test = JSON.parse(JSON.stringify(jfile))

console.log(test)

I get the output like this:

{ Data:
   [ { name: 'John', age: 30 },
     { 'joined on': 'Jan 2015', 'working on': 'Automation' } ] }

From the above, I am interested in accessing/filtering out only one i.e. "name". I would like to print only the value "John" to the console.

I have tried to use the ".filter" method to the JSON.parse method but it throws me an error as:

JSON.parse(...).filter is not a function

Is there any way to perform this activity?

@Quentin - I am very new to JSON and still learning, saw at various places to use it this way, Hence I tried to implement the same — Adarsh Kumar GM
– Adarsh Kumar GM, Commented Feb 18, 2019 at 10:55

ellipsis · Accepted Answer · 2019-02-18 10:53:39Z

2

You can access it using . dot notation

var a = {
  "Data": [{

      "name": "John",
      "age": 30
    },

    {
      "joined on": "Jan 2015",
      "working on": "Automation",
    }
  ]
}
console.log(a.Data[0].name)

answered Feb 18, 2019 at 10:53

ellipsis

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1 Comment

Adarsh Kumar GM Over a year ago

I have the values in a separate JSON file and I am trying to access these objects in my javascript file. Does the dot notation still work ?

Quentin · Accepted Answer · 2019-02-18 10:54:22Z

0

filter is an array method.

JSON.parse(...) will not give you an array. It will give you an object with a Data property. The value of that property is an array.

JSON.parse(...).Data.filter.

You can't just ignore parts of your data structure.

answered Feb 18, 2019 at 10:54

community wiki

Quentin

Comments

molamk · Accepted Answer · 2019-02-18 10:57:20Z

0

If you have multiple items in your array of different shapes, you can use this

Access the Data key with json.Data
map your array to transform its items into names
apply filter(Boolean) to take out those who are undefined

In your case you'll end up with an array containing only one name John

const getName = json => json.Data.map(x => x.name).filter(Boolean);

const json = {
  "Data": [{

      "name": "John",
      "age": 30
    },

    {
      "joined on": "Jan 2015",
      "working on": "Automation",
    }
  ]
};

console.log(getName(json));

answered Feb 18, 2019 at 10:57

molamk

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Comments

FZs · Accepted Answer · 2019-02-18 11:01:09Z

0

Your JSON's main level is an object (not an array) and only arrays have .filter method.
So filter the array under Data key:

var test = JSON.parse(JSON.stringify(jfile)).Data.filter(/*something*/);

But better if you aren't re-parse JSON:

var test = jfile.Data.filter(/*something*/);

answered Feb 18, 2019 at 11:01

FZs

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Comments

Rohìt Jíndal · Accepted Answer · 2019-02-18 11:55:01Z

0

As Quentin mentioned in his comment, What is the use of below statement ?

var test = JSON.parse(JSON.stringify(jfile))

You can directly access the name property from the response.

Try this :

var obj = {
	"Data": [{

			"name": "John",
			"age": 30
		},

		{
			"joined on": "Jan 2015",
			"working on": "Automation"
		}
	]
};

// Solution 1
console.log(obj.Data.map(item => item.name).filter(Boolean));

// Solution 2
console.log(obj.Data.filter(item => item.name).map(elem => elem.name));

answered Feb 18, 2019 at 11:55

Rohìt Jíndal

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2 Comments

HazimoRa3d Over a year ago

Why adding json in a variable? what about a local json file with million of lines, how to load it and apply filter on it ?

Rohìt Jíndal Over a year ago

In OP, there is a small JSOn that's the only reason i put that in a variable. Its all about the requirement.

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