Remove repeating elements in an array

Question

for(var i=0;i<d.length;i++)
{
  current=d[i].businessunits;
  arraynew.push(current);//array new like this {0:EU;1:PU;2:MS;3:EU;4:PU}
}

I have an array var k={"Eu","PU","MS","EU","PU"} and I need only EU PU MS because EU and PU are Repeating.How to remove the Repeating Elements in an array.

Answer 1

Check element already exist in an array before pushing the value.

for(var i=0;i<d.length;i++)
{
  current=d[i].businessunits;
  if(arraynew.indexOf(current) === -1) arraynew.push(current);//array new like this {0:EU;1:PU;2:MS;3:EU;4:PU}
}

Answer 2

With ES6, you could use Set, because set keeps only one element of the same.

Solution for all upper case.

var k = ["EU", "PU", "MS", "EU", "PU"];

k = [... new Set(k)];
console.log(k);

Solution for mixed case.

var k = ["Eu", "PU", "MS", "EU", "PU"];

k = [... new Set(k.map(a => a.toUpperCase()))];
console.log(k);

Answer 3

work on all browsers:

myArray.filter(function (x, i, a) { 
    return a.indexOf(x) == i; 
});

for modren browsers

[...new Set(myArray)]

Answer 4

Hashtables are a good tool for this. Here is some pseudocode:

1. Iterate over the array and add each item into the hashtable as a key if it doesn't already exist
2. Return a list of the keys in the hashtable.

If you are using a language which supports sets, it is even easier- simply update the set once for each element in the array.

Answer 5

Simple solution using Array.forEach and Array.indexOf functions:

var arr = ["Eu","PU","MS","EU","PU"], result = [];

arr.forEach(function(v){
    result.indexOf(v.toUpperCase()) === -1 && result.push(v.toUpperCase());
});

console.log(result);

Answer 6

Following code check before adding element in new array so. new array not contains repeating elements

for(var i=0;i<d.length;i++)
{
   current=d[i].businessunits;
   if(arraynew.indexOf(current) === -1) // if new array not contains element add in new array 
      arraynew.push(current);
}

Answer 7

You can sort the array and push non matching elements.

Sort + array.reduce

var a = ["EU", "PU", "MS", "EU", "PU"];
var r = [];
a.sort().reduce(function(p,c){
  if(p!==c) r.push(c)
  return c;
}, '');

console.log(r)

Sort + for

var a = ["EU", "PU", "MS", "EU", "PU"];
var r = [a[0]];
a.sort()

for(var i = 0; i<a.length -2; i++){
    if(a[i] !== a[i+1]) r.push(a[i+1])
}
console.log(r)

Answer 8

Easy solution

var checkDuplicateObject = {},arraynew = [];
for(var i=0;i<d.length;i++)
{
   if(checkDuplicateObject(d[i].businessunits)){
   }else{
    var current = d[i].businessunits;
    arraynew.push(current);  
    checkDuplicateObject[d[i].businessunits] = true;
  }
}