Javascript: removing elements from Json by value

Question

I need to remove elements from a json string returned by an AJAX call.

I'm not sure how to loop through the string and remove all elements where the value i NULL.

My json looks like this.

[
 {"ID":"27","Agility":"15","Balance":null,"Strength":"37","Physiology":"32"},
 {"ID":"30","Agility":"27","Balance":null,"Strength":null,"Physiology":null},
 {"ID":"34","Agility":null,"Balance":null,"Strength":null,"Physiology":null},
 {"ID":"36","Agility":null,"Balance":null,"Strength":null,"Physiology":null},
 {"ID":"40","Agility":null,"Balance":"20","Strength":null,"Physiology":"34"},
 {"ID":"42","Agility":null,"Balance":"16","Strength":null,"Physiology":null},
 {"ID":"51","Agility":null,"Balance":null,"Strength":"39","Physiology":null}
]

I thought I might do something like this for every key but i would prefer a generic function:

if(json[index].Strength == null){
    json.splice(index,1);
}

So you want to remove the object if any of its keys is null ? — cyr_x
– cyr_x, Commented Feb 24, 2018 at 10:58
That was the idea. if it was not possible I would go with a line for every key. — Flemming Lemche
– Flemming Lemche, Commented Feb 24, 2018 at 11:03

Nenad Vracar · Accepted Answer · 2018-02-24 11:02:07Z

2

You can parse json with JSON.parse method and then use filter() method on that array.

const json = '[{"ID":"27","Agility":"15","Balance":null,"Strength":"37","Physiology":"32"},{"ID":"30","Agility":"27","Balance":null,"Strength":null,"Physiology":null},{"ID":"34","Agility":null,"Balance":null,"Strength":null,"Physiology":null},{"ID":"36","Agility":null,"Balance":null,"Strength":null,"Physiology":null},{"ID":"40","Agility":null,"Balance":"20","Strength":null,"Physiology":"34"},{"ID":"42","Agility":null,"Balance":"16","Strength":null,"Physiology":null},{"ID":"51","Agility":null,"Balance":null,"Strength":"39","Physiology":null}]'

const data = JSON.parse(json).filter(o => o.Strength != null)
console.log(data)

If you want to remove elements where some property has value of null you can use some method inside filter.

const json = '[{"ID":"27","Agility":"15","Balance":null,"Strength":"37","Physiology":"32"},{"ID":"30","Agility":"27","Balance":null,"Strength":null,"Physiology":null},{"ID":"34","Agility":null,"Balance":null,"Strength":null,"Physiology":null},{"ID":"36","Agility":null,"Balance":null,"Strength":null,"Physiology":null},{"ID":"40","Agility":null,"Balance":"20","Strength":null,"Physiology":"34"},{"ID":"42","Agility":null,"Balance":"16","Strength":null,"Physiology":null},{"ID":"51","Agility":null,"Balance":null,"Strength":"39","Physiology":null}]'

const data = JSON.parse(json).filter(o => {
  return !Object.keys(o).some(k => o[k] == null)
})
console.log(data)

answered Feb 24, 2018 at 11:02

Nenad Vracar

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1 Comment

Flemming Lemche Over a year ago

Hi Nenad. Thank you for your suggestions. They works fine but I think that I did not explain myself enough. :( I wanted to remove all entries with the value of null but keep the rest of the entries. So: {"ID":"30","Agility":"27","Balance":null,"Strength":null,"Physiology":null} Would be reduced to: {"ID":"30","Agility":"27"} My apologies for the unclear explanation.

Jaye Renzo Montejo · Accepted Answer · 2018-02-24 11:01:24Z

1

Use filter:

const newJson = json.filter(item => item.Strength !== null)

answered Feb 24, 2018 at 11:01

Jaye Renzo Montejo

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Comments

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

If you prefer a generic function, Lodash is the best option.

PickBy picks up properties from an object, based on a Predicate.
Here predicate is Identity, which means, pickup non null properties from the object.

var jsonResponse = '[{"ID":"27","Agility":"15","Balance":null,"Strength":"37","Physiology":"32"},{"ID":"30","Agility":"27","Balance":null,"Strength":null,"Physiology":null},{"ID":"34","Agility":null,"Balance":null,"Strength":null,"Physiology":null},{"ID":"36","Agility":null,"Balance":null,"Strength":null,"Physiology":null},{"ID":"40","Agility":null,"Balance":"20","Strength":null,"Physiology":"34"},{"ID":"42","Agility":null,"Balance":"16","Strength":null,"Physiology":null},{"ID":"51","Agility":null,"Balance":null,"Strength":"39","Physiology":null}]';

var responseArr = JSON.parse(jsonResponse);

// Only lines that matter
responseArr = _.map(responseArr, function(obj) {
  return _.pickBy(obj, _.identity);
});

console.log("Array of Objects: ", responseArr);
console.log("JSON: ", JSON.stringify(responseArr));

<script src="https://cdn.jsdelivr.net/npm/[email protected]/lodash.min.js"></script>

Put the above mentioned script tag just before closing tag of your html page.

So just loop through the whole array response using map, and apply PickBy on each object of the array, and you have yourself an array of sparse objects.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Feb 24, 2018 at 12:13

Abhijit Kar ツ

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2 Comments

Flemming Lemche Over a year ago

It seem what I'm looking for based on the code snippet but I get an error when using your code. Uncaught ReferenceError: _ is not defined

Abhijit Kar ツ Over a year ago

Oh, you have to use lodash for this to work <script src="cdn.jsdelivr.net/npm/[email protected]/lodash.min.js"></…> Dependencies are mentioned just above the Run code snippet button

Rohìt Jíndal · Accepted Answer · 2018-02-26 07:19:14Z

0

Try Array filter() method with ES6 Arrow function.

Demo

var jsonObj = [
 {"ID":"27","Agility":"15","Balance":null,"Strength":"37","Physiology":"32"},
 {"ID":"30","Agility":"27","Balance":null,"Strength":null,"Physiology":null},
 {"ID":"34","Agility":null,"Balance":null,"Strength":null,"Physiology":null},
 {"ID":"36","Agility":null,"Balance":null,"Strength":null,"Physiology":null},
 {"ID":"40","Agility":null,"Balance":"20","Strength":null,"Physiology":"34"},
 {"ID":"42","Agility":null,"Balance":"16","Strength":null,"Physiology":null},
 {"ID":"51","Agility":null,"Balance":null,"Strength":"39","Physiology":null}
];

var res = jsonObj.filter(elem => elem.Strength !== null);

console.log(res);

answered Feb 26, 2018 at 7:19

Rohìt Jíndal

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3 Comments

Flemming Lemche Over a year ago

I get an error when using your code: Uncaught TypeError: response.filter is not a function. I can also see that PHPStorm gives an error in the code on the "=>". It says "Expression Expected" what am I missing ??

Rohìt Jíndal Over a year ago

@FlemmingLemche I did not use any response.filter in my code then how it is possible to get error on that ? You can run the code snippet in my answer it is working fine .

Flemming Lemche Over a year ago

I forgot to use .parseJSON before running your code.

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