Compare each item in an array of objects

Question

I have an array of objects:

   const array = [{ 
    "colour": "red",
    "job": "student",
    "title": "Mr",
},
 {
    "colour": "green",
    "job": "student",
    "title": "",
},
{
    "colour": "",
    "job": "teacher",
    "title": "Mr",
},  
{
    "colour": "red",
    "job": "student",
    "title": "Mr",
}}]

I would like to compare the objects inside the array with each other.

What I have so far does not seem efficient as I would be comparing index i=1 and j=2 and i=2 and j=1 which is comparing exactly the same object. I am using Lodash _.isEqual() to compare the objects.

 const handleArrayItems = () => {
    for (let i = 0; i <= array.length; i++) {
        for (let j = 1; j < array.length; j++) {
            if (j === i) {
                continue; //to avoid comparing same object
            }
            if (_.isEqual(array[j],array[i])) {
                return true;
            }
        }
    }   
 };

Based on what is returned from above, it is passed into an if/else statement.

if (handleArrayItems()) {
  console.log("found a duplicate item in array")
}

handleArrayItems() will return true if there is a match and false is no object items are the same — programhur
– programhur, Commented Oct 25, 2021 at 4:49

CertainPerformance · Accepted Answer · 2021-10-25 04:45:12Z

1

Separate objects are not equal to each other.

if (_.isEqual(array[j] === array[i])) {

will evaluate the argument first:

array[j] === array[i]

which is false, resulting in:

if (_.isEqual(false)) {

which doesn't work.

You need to pass both values to isEqual for comparison

if (_.isEqual(array[j], array[i])) {

so that Lodash can compare the values itself.

answered Oct 25, 2021 at 4:45

CertainPerformance

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Comments

vincrichaud · Accepted Answer · 2021-10-25 13:01:16Z

0

Make j goes from i+1 to array.length to doing comparison twice.

And i can go to length-1 only, since j will go to the end.

for (let i = 0; i <= array.length-1; i++) {
    for (let j = i+1; j < array.length; j++) {

answered Oct 25, 2021 at 13:01

vincrichaud

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