CODEWITHSUNDEEP
javascript
lili
lili

Reputation: 63

Find duplicate values inside array of objects

What is the best way in JavaScript to go over array of object and check if an certain value already exist in one of the property of the array objects? For example: I have array of objects as follow: [{name:"team1",members:3},{name:"bestteam",members:4}] Now I want to add a new object but I want to check that this object property "name" do not exist in the array before adding it

Upvotes: 1

Views: 17300

Answers (5)

Mike Kor
Mike Kor

Reputation: 876

You can use simple loops. Here is function which should help you to find out if key value is in array.

function keyExist(value, array) {
    for(var i in array) {
        for(var k in array[i])
            if(array[i][k] === value) {
                console.log(value + ' is in array!');

                return true;
            }
    }

    return false;
}

As for you example you can change second loop

for(var k in array[i])
    if(k === value) { return true; }

to 

if(array[i].name === value) { return true; }

Upvotes: 1

Jairo
Jairo

Reputation: 426

Try this

function checkIfNameExists(arr, newName) {
    return arr.some(function(e) {
        return e.name === newName;
    });
}

where arr is your array and newName is the name to check.

You could also make it less ad hoc by passing the property to compare as a parameter, like so

function checkIfNameExists(arr, prop, newVal) {
    return arr.some(function(e) {
        return e[prop] ? e[prop] === newVal : false;
    });
}

Upvotes: 3

Nina Scholz
Nina Scholz

Reputation: 386522

You can iterate over the array and iterate over the keys of the array and check if some properties have the wanted value.

var data = [{ prop1: 'one', prop2: 'two' }, { prop3: 'three', prop4: 'four' }];

function find(v, data) {
    data.forEach(function (a, i) {
        Object.keys(a).forEach(function (k) {
            if (a[k] === v) {
                document.write(v + ' found in [' + i + '].' + k);
            }
        });
    });
}

find('three', data);

Upvotes: 1

Patrick Kelleter
Patrick Kelleter

Reputation: 2771

assuming you say an object equals an object if and only if they have the exact same elements and values for each element:

var map = {};
for (var i = 0; i < arr.length; i++) {
    var index = JSON.stringify(arr[i]);
    if (!map[index]) {
        map[index] = 1;
    } else {
        map[index]++;
    }
}
for (var key in map) {
    if (map[key] > 1) {
        console.log ('duplicate found for:');
        console.log (JSON.parse (key));
    }
}

simply define an array "arr" with some objects and check it out

Upvotes: 1

Valentin Petkov
Valentin Petkov

Reputation: 1648

I have no time to respond but here from my previous code maybe some will optimize it...

 function JSONRemoveDuplicates(JSONDATA) {
    var uniqueNames = [];
    $.each(JSONDATA, function (i, el) {
        if (!existInJSON(uniqueNames, el) > 0) { uniqueNames.push(el); }
    });
    return uniqueNames;
}


function existInJSON(jsondata, el) {
    var ret = 0;
    $(jsondata).each(function (index, data) {
        if (data.id == el.id)
            ret++;
    })
    return ret > 0;
}

Upvotes: 0

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