Remove duplicates of single "a" value from array if array has multiple "a" elements

Question

I am looking for a simple solution. I have an array like array("a","b","c","a","g");

Now when i try splice or custom remove function , it removes all "a" elements from array.

What i want is when i remove "a" from the array , then the array should finally have 1 "a" element only inside it and remove all other dulicates of "a".

Now consider another case , when my array is like array("a","a","b","c","a") , then after removing "a" , the array should like array("a","b","c").

Help needed,

Thanks in advance

Possible duplicate of How to remove a particular element from an array in JavaScript? — Hatted Rooster
– Hatted Rooster, Commented Sep 20, 2016 at 8:35
@GillBates : I have updated my question. Can you check now please. — BeingExpert
– BeingExpert, Commented Sep 20, 2016 at 8:37
Still the same question, just use array.indexOf("a") and then array.splice(index, 1); — Hatted Rooster
– Hatted Rooster, Commented Sep 20, 2016 at 8:39
@GillBates : I think you still getting it wrong or i may be wrong but splice remove all same elements from array for me. i have used same array.splice(index, 1) . — BeingExpert
– BeingExpert, Commented Sep 20, 2016 at 8:41

cheralathan · Accepted Answer · 2016-09-20 08:44:22Z

0

Try this snippet

var arr = ["a","a","b","c","a"];
var arrayLength = arr.length;

for (var i = 0; i < arrayLength; i++) {
  for (var j = i + 1; j < arrayLength;) {
    if (arr[j] == arr[i]) {
      for (var k = j; k < arrayLength; k++) {
        arr[k] = arr[k + 1];
      }
      arrayLength--;
    } else
      j++;
  }
}

var newArr = [];
for (var i = 0; i < arrayLength; i++) {
  newArr.push(arr[i]);
}
console.log(newArr);

answered Sep 20, 2016 at 8:44

cheralathan

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Comments

Michael Troger · Accepted Answer · 2016-09-20 08:53:20Z

0

You can make use of the filter method like:

var duplicates = ["a","a","b","c","a"];
var withoutDuplicates = duplicates.filter(function(currentValue, index) {
    return duplicates.indexOf(currentValue) == index;
});
console.log(withoutDuplicates); // Array [ "a", "b", "c" ]

As also stated here: Remove Duplicates from JavaScript Array

Documentation: http://www.w3schools.com/jsref/jsref_filter.asp

edited Sep 20, 2016 at 8:53

answered Sep 20, 2016 at 8:43

Michael Troger

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Comments

Nina Scholz · Accepted Answer · 2016-09-20 11:02:53Z

0

You could use Set and keep only unique items in the array.

var unique = array => array.filter((set => a => !set.has(a) && set.add(a))(new Set));

console.log(unique(["a", "b", "c", "a", "g"]));
console.log(unique(["a", "a", "b", "c", "a"]));

Different style

var unique = function (array) {
        return array.filter(function (a) {
            if (!this.has(a)) {
                this.add(a);
                return true;
            }
        }, new Set);
    };

console.log(unique(["a", "b", "c", "a", "g"]));
console.log(unique(["a", "a", "b", "c", "a"]));

ES5 with Object as hash

var unique = function (array) {
        return array.filter(function (a) {
            if (!this[a]) {
                return this[a] = true;
            }
        }, Object.create(null));
    };

console.log(unique(["a", "b", "c", "a", "g"]));
console.log(unique(["a", "a", "b", "c", "a"]));

edited Sep 20, 2016 at 11:02

answered Sep 20, 2016 at 8:41

Nina Scholz

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4 Comments

BeingExpert Over a year ago

This is the solution what i was expecting. Thanks

BeingExpert Over a year ago

The above code is not working for NodeJs. May be i am missing correct syntax.

Nina Scholz Over a year ago

please try the second proposal.

Nina Scholz Over a year ago

please try the third one.

Shaishab Roy · Accepted Answer · 2016-09-20 11:24:39Z

0

Can try this one

var array = ["a","a","b","c","a"];

var filterIfMultiple = function (data) {
  var count = 0;
  array = array.filter(function(val) {
              if (val === data) count+=1; 
              if(val !== data || (val === data && count <= 1)){
                 return val;
              }
          });
};

filterIfMultiple("a");
console.log(array);

Another process without passing any parameter using ES6 Set object

var array = ["a","a","b","c","a","b"];

function filterIfDuplicate() {
   array = Array.from(new Set(array));
}

filterIfDuplicate();
console.log(array);

edited Sep 20, 2016 at 11:24

answered Sep 20, 2016 at 9:28

Shaishab Roy

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2 Comments

BeingExpert Over a year ago

can we customize above function to automatically detect all duplicates ,basically i can not send one parameter , it can be anything.

Shaishab Roy Over a year ago

can try second process without passing any parameters @ShashikantSharma

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