Exploring discrepancies in JSON arrays using Lodash

Question

Exploring discrepancies in JSON arrays using Lodash

Using lodash to find the difference between two arrays:

c1Arr contains:

[ { varName: 'city', varValue: 'cccccccc' },
  { varName: 'country', varValue: 'dddddddd' }
 ]

c2Arr contains:

[ { varName: 'abc', varValue: 'aaa' },
  { varName: 'city', varValue: 'cccccccc' },
  { varName: 'country', varValue: 'dddddddd' }
 ]

When running this code snippet:

    var dArr = _.difference(c2Arr, c1Arr);
    console.log(dArr);

Instead of getting the expected result:

[ { varName: 'abc', varValue: 'aaa' }]

I am getting (i.e. c2Arr in total):

[ { varName: 'abc', varValue: 'aaa' },
  { varName: 'city', varValue: 'cccccccc' },
  { varName: 'country', varValue: 'dddddddd' }
 ]

javascript json lodash array-difference

Answer 1

Answer №1

To handle objects as elements, you must define the comparator function.

Give this a try:

_.differenceWith(c2Arr, c1Arr, _.isEqual);

var c1Arr = [{
  varName: 'city',
  varValue: 'cccccccc'
}, {
  varName: 'country',
  varValue: 'dddddddd'
}]

var c2Arr = [{
  varName: 'abc',
  varValue: 'aaa'
}, {
  varName: 'city',
  varValue: 'cccccccc'
}, {
  varName: 'country',
  varValue: 'dddddddd'
}]

var dArr = _.differenceWith(c2Arr, c1Arr, _.isEqual);
console.log(dArr);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Answer 2

To handle objects as elements, you must define the comparator function.

Give this a try:

_.differenceWith(c2Arr, c1Arr, _.isEqual);

var c1Arr = [{
  varName: 'city',
  varValue: 'cccccccc'
}, {
  varName: 'country',
  varValue: 'dddddddd'
}]

var c2Arr = [{
  varName: 'abc',
  varValue: 'aaa'
}, {
  varName: 'city',
  varValue: 'cccccccc'
}, {
  varName: 'country',
  varValue: 'dddddddd'
}]

var dArr = _.differenceWith(c2Arr, c1Arr, _.isEqual);
console.log(dArr);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Exploring discrepancies in JSON arrays using Lodash

Answer №1

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