how to remove duplicate elements in an array in javascript code example

Example 1: javascript remove duplicate in arrays

// 1. filter()
function removeDuplicates(array) {
  return array.filter((a, b) => array.indexOf(a) === b)
};
// 2. forEach()
function removeDuplicates(array) {
  let x = {};
  array.forEach(function(i) {
    if(!x[i]) {
      x[i] = true
    }
  })
  return Object.keys(x)
};
// 3. Set
function removeDuplicates(array) {
  array.splice(0, array.length, ...(new Set(array)))
};
// 4. map()
function removeDuplicates(array) {
  let a = []
  array.map(x => 
    if(!a.includes(x) {
      a.push(x)
    })
  return a
};
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Example 2: javascript remove duplicates from array

unique = [...new Set(arr)];   // where arr contains duplicate elements

Example 3: remove duplicates array javascript

var data = [1, 2, 'Peter', 3, 3,'Peter', 2, 2, 1, 2, 3, 4, 4, 5, 4];
var unique = data.filter((v, i, a) => a.indexOf(v) === i);

Example 4: how to get unique values from array in javascript without duplicate value

function uniqueArray2(arr) {
    var a = [];
    for (var i=0, l=arr.length; i<l; i++)
        if (a.indexOf(arr[i]) === -1 && arr[i] !== '')
            a.push(arr[i]);
    return a;
}