Filter array to have unique values

Question

I need to filter out my array to contain only unique values  this is my array data    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11     expected result should be    X row7    X row4    X row6    X row10    X row11    X row8    X row9     How should i continue my code to get proper result   newArray       for n in data     if  newArray indexOf n         newArray push n         console log newArray     If you need any additional information s please let me know and i will provide  thank you

User · Answer

You can use Map and Spread Operator    x000D   x000D  var rawData     X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    x000D   x000D  var unique   new Map    x000D  rawData forEach d   gt  unique set d  d    x000D  var uniqueItems       unique keys     x000D   x000D  console log uniqueItems   x000D   x000D   x000D

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As of June 15  2015 you may use Set   to create a unique array   var uniqueArray       new Set array       For your Example   var data     X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11   var newArray       new Set data   console log newArray    gt  gt    X row7    X row4    X row6    X row10    X row8    X row9    X row11

User · Answer

A slight variation on the indexOf method  if you need to filter multiple arrays   function unique item  index  array        return array indexOf item     index      Use as such   arr filter unique

User · Answer

Array prototype unique   function        return     new Set this       then we can write   const arr    1  5  2  2  2  3  4  3  2  1  5  const uniqueArr   arr unique

User · Answer

You can use reduce to loop the array and get the not duplicate values  Also uses an aux object to get the count of added values   x000D   x000D  var aux       x000D   x000D  var newArray     X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11   reduce  tot  curr   gt   x000D    if  aux curr    x000D      aux curr    1  x000D      tot push curr   x000D      x000D    return tot  x000D          x000D   x000D  console log newArray   x000D   x000D   x000D

User · Answer

I ve always used   unique    arr    gt  arr filter  item  i  s    gt  s lastIndexOf item     i     But recently I had to get unique values for     1   1   2   2   3   3    And my old standby didn t cut it  so I came up with this   uunique    arr    gt  Object keys Object assign        arr map a  gt    a  true

User · Answer

You could use a hash table for look up and filter all not included values    x000D   x000D  var data     X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    x000D      unique   data filter function  a    x000D          return  this a   amp  amp   this a    true   x000D         Object create null    x000D   x000D  console log unique   x000D   x000D   x000D

User · Answer

This is for es2015 and above as far as I know  There are  cleaner  options with ES6 but this a great way to do it  with TypeScript    let values  any         const distinct    value  any  index  any  self  any    gt        return self indexOf value      index     values   values filter distinct

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Filtering an array to contain unique values can be achieved using the JavaScript Set and Array from method  as shown below   Array from new Set arrayOfNonUniqueValues     Set     The Set object lets you store unique values of any type  whether   primitive values or object references       Return value A new Set object    Array from       The Array from   method creates a new Array instance from an   array-like or iterable object       Return value A new Array instance    Example Code    x000D   x000D  const array     X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11   x000D   x000D  const uniqueArray   Array from new Set array    x000D   x000D  console log  uniqueArray     uniqueArray   x000D   x000D   x000D

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x000D   x000D  arr     I    do    love    JavaScript    and    I    also    do    love    Java    x000D   x000D  uniqueArr        new Set arr    x000D   x000D     or x000D   x000D  reallyUniqueArr   arr filter  item  pos  ar    gt  ar indexOf item      pos  x000D   x000D  console log    uniqueArr  n  reallyUniqueArr    x000D   x000D   x000D

User · Answer

You can use Array filter function to filter out elements of an array based on the return value of a callback function  The callback function runs for every element of the original array   The logic for the callback function here is that if the indexOf value for current item is same as the index  it means the element has been encountered first time  so it can be considered unique  If not  it means the element has been encountered already  so should be discarded now    x000D   x000D  var arr     X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    X row7    X row4    X row6    X row10    X row8    X row9    X row11    x000D   x000D  var filteredArray   arr filter function item  pos   x000D    return arr indexOf item    pos   x000D      x000D   x000D  console log  filteredArray    x000D   x000D   x000D    Caveat  As pointed out by rob in the comments  this method should be avoided with very large arrays as it runs in O N 2    UPDATE  16 Nov 2017   If you can rely on ES6 features  then you can use Set object and Spread operator to create a unique array from a given array  as already specified in  Travis Heeter s answer below   var uniqueArray       new Set array

[javascript] Filter array to have unique values

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