Increment value of one element of an JSON array of objects

Question

I have a JSON, which contains id and points. if the ID matches, i need to increase with 1. IF the id does not match i need to push to a new empty array

Here what I have tried. but it is not working

var points = [{
  id: 1,
  point: 0
}, {
  id: 2,
  point: 0
}, {
  id: 3,
  point: 1
}]

var data = {
  id: 1
}

if (!(points.length)) {
  points.push(data)
} else {
  if (points.find(e => e.id === data.id)) {
    var m = points.find(e => e)
    console.log(m.id)
    m.point+= 1
  } else {
    points.push(data)
  }
}

There's nothing like a "JSON array". points is an array of objects. — Andreas
– Andreas, Commented Feb 1, 2018 at 17:32
m = points.find(e => e) that is wrong. You need to do the same test in the callback as in the if condition. Of course, you should rewrite it so to have to do that only once. — trincot
– trincot, Commented Feb 1, 2018 at 17:41
@MunimMunna It only works if the id in data is the same as the id of the first element in points — Andreas
– Andreas, Commented Feb 1, 2018 at 17:41

wilovent · Accepted Answer · 2018-02-13 17:07:21Z

2

You're always increasing the first element of the array

var m = points.find(e => e)
=>
var m = points.find(e => e.id === data.id)

find need a predicate that return true or false given an element. In the first line, it always return the element itself which is a truthy value. So the first element is return

edited Feb 13, 2018 at 17:07

answered Feb 1, 2018 at 17:42

wilovent

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1 Comment

wilovent Over a year ago

Because find need a predicate that return true or false given an element. In the first line, it always return the element itself which is a truthy value. If this solvers your problem, can you please accept the answer (white check mark below the up/down-vote buttons) to indicate this question is answered. Thanks.

vatz88 · Accepted Answer · 2018-02-01 17:53:17Z

1

The find method on array returns a value and not boolean as you maybe are trying to use in this case. It'll return undefined if no value matches.

Also you don't really need the outer if and nest one more inside it.

var points = [{
  id: 1,
  point: 0
}, {
  id: 2,
  point: 0
}, {
  id: 3,
  point: 1
}]

var data = {
  id: 1
}

let temp = points.find(e => e.id === data.id)
if (temp != undefined) { // This is just for understanding. `undefined` inside `if` will give false. So you can use `if(!temp)`
  temp.point+= 1
} else {
  points.push(data)
}

console.log(points);

edited Feb 1, 2018 at 17:53

answered Feb 1, 2018 at 17:42

vatz88

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2 Comments

Andreas Over a year ago

undefined is a falsy value which will evaluate as false, hence there's no need to explicitly test for undefined. The real solution in your answer is unmentioned and unexplained.

vatz88 Over a year ago

@Andreas I'm testing it explicitly just to explain that it'll return undefined if no value is found. Added a comment for that. In the question find method is used twice with if and again inside the if which is actually not needed. includes is more appropriate method to use with conditionals than find.

danh · Accepted Answer · 2018-02-01 17:54:53Z

1

The new data needs a point property, and you could clean the code up a little to be clearer about intent...

var points = [{
  id: 1,
  point: 0
}, {
  id: 2,
  point: 0
}, {
  id: 3,
  point: 1
}]

var data = {
  id: 1
}

// we have a data object.  if it's new (not found in points) add it with a point count of 0
// if it exists (we find it in points array) increment point for the existing element

let matchingPoint = points.find(p => p.id === data.id);
if (!matchingPoint) {
    data.point = 0;
    points.push(data);
} else {
    matchingPoint.point += 1;
}
console.log(points)

edited Feb 1, 2018 at 17:54

answered Feb 1, 2018 at 17:43

danh

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Comments

Gopi Gorantala · Accepted Answer · 2018-10-11 13:04:28Z

0

Creating an object:

tagObject = {};
tagObject['contentID'] = [];  // adding an entry to the above tagObject
tagObject['contentTypes'] = []; // same explanation as above
tagObject['html'] = [];

Now below is the occurrences entry which I am addding to the above tag Object..

ES 2015 standards: function () {} is same as () => {}

      let found = Object.keys(tagObject).find(
            (element) => {
                return element === matchWithYourValueHere;
            });

      tagObject['occurrences'] = found ? tagObject['occurrences'] + 1 : 1;

this will increase the count of a particular object key..

answered Oct 11, 2018 at 13:04

Gopi Gorantala

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