How to remove duplicates from an array object property value?

Question

How can I iterate through object properties and remove duplicates from an array that is the value of that object property?

Original object

var navObjects = {
    'Components': ['x', 'y', 'x'],
    'Document': ['z', 'z', 'z', 'q'],
    'Utilities': ['a', 'b', 'c']
}

Desired object

navObjects: {
    'Components': ['x', 'y'],
    'Document': ['z','q'],
    'Utilities': ['a', 'b', 'c']
}

What I've tried

for (let i = 0; i < Object.values(navObjects).length; i++) {

    let obj = Object.values(navObjects)[i];

    Object.values(obj).filter((item, index) => obj.indexOf(item) === index);
    console.log(obj);

}

The arrays remain unchanged after running this block.

0xdw · Accepted Answer · 2019-08-04 16:23:12Z

4

You can do it using the Set constructor and the spread syntax:

const navObjects = {
  'Components': ['x', 'y', 'x'],
  'Document': ['z', 'z', 'z', 'q'],
  'Utilities': ['a', 'b', 'c']
};

for (const key in navObjects) {
  navObjects[key] = [...new Set(navObjects[key])];
}

console.log(navObjects);

answered Aug 4, 2019 at 16:23

0xdw

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2 Comments

Will Jenkins Over a year ago

Nice. This wins.

Lajos Arpad Over a year ago

This will only work if we assume that the object only has array members and we intend to remove duplicates for all of them.

William Gunawan · Accepted Answer · 2019-08-04 16:14:36Z

0

This code will help you to achieve your objective.

var newNavObjects = {}
var existObjects = {}
for(let key in navObjects) {
    let objects = navObjects[key];
    newNavObjects[key] = [];
    existObjects[key] = {};
    for(let object of objects) {
        if (!existObjects[key][object]) {
            existObjects[key][object] = 1;
            newNavObjects[key].push(object);
        }
    }
}
delete existObjects;
console.log(newNavObjects);

I create new variable for efficiency. If we use indexOf to check value inside array exist of not. It will heavier than we check an target variable key in this case existObjects. Still this not the best solution but this sure will do. :)

answered Aug 4, 2019 at 16:14

William Gunawan

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Comments

Lajos Arpad · Accepted Answer · 2019-08-04 16:22:56Z

0

You can create a Set to remove duplicates and get values() in order to convert it back to an array, like:

(new Set(['z', 'z', 'z', 'q'])).values()

Let's make a function of it:

function removeDuplicates(input) {
    return (new Set(input)).values();
}

and then use it:

var navObjects = {
    'Components': removeDuplicates(['x', 'y', 'x']),
    'Document': removeDuplicates(['z', 'z', 'z', 'q']),
    'Utilities': removeDuplicates(['a', 'b', 'c'])
}

answered Aug 4, 2019 at 16:22

Lajos Arpad

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1 Comment

Lajos Arpad Over a year ago

I wonder about the reason this answer was downvoted. I tested it and it worked. If someone would shed light on the reason, I would be grateful.

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