Array push and unique items

Question

I have a simple case of pushing unique values into array  It looks like this     this items          add item        if this items indexOf item   gt  -1          this items push item         console log this items               Seems pretty straight-forward  right  No  as it appears  It doesn t add any values  I am sure it s some kind of silly mistake on my side  but I can t seem to find it

User · Answer

Using Set  this items   new Set    this items add 1   this items add 2   this items add 1   this items add 2    console log Array from this items        1  2

User · Answer

You can use the Set structure from ES6 to make your code faster and more readable     Create Set this items   new Set     add item        this items add item           Set to array     console log     this items

User · Answer

Push always unique value in array  ab            id   1   val   value1           id   2   val   value2           id   3   val   value3            var clickId       var list   JSON parse ab     each list  function index  value       if clickId indexOf value id   lt  0           clickId push value id

User · Answer

so not sure if this answers your question but the indexOf the items you are adding keep returning -1   Not to familiar with js but it appears the items do that because they are not in the array yet  I made a jsfiddle of a little modified code for you   this items        add 1   add 2   add 3    document write  added items to array    document write   lt br gt     function  add item              document write this items indexOf item        if this items indexOf item   lt   -1           this items push item           document write  Hello World              document write  array is       this items     https   jsfiddle net jmpalmisano Lnommkbw 2

User · Answer

Yep  it s a small mistake   if this items indexOf item      -1        this items push item       console log this items

User · Answer

var helper       for var i   0  i  lt  data length  i       helper data i     1     Fill object   var result   Object keys helper      Unique items

User · Answer

You have to use     -1  if it equals to -1 i e  item is not available in your array     this items          add item        if this items indexOf item      -1          this items push item         console log this items

User · Answer

In case if you are looking for one liner For primitives this items indexOf item      -1   amp  amp  this items push item    For objects this items findIndex  item  ItemType    gt  item var     checkValue      -1  amp  amp  this items push item

User · Answer

try  includes     1  2  3  includes 2          true  1  2  3  includes 4          false  1  2  3  includes 3  3       false  1  2  3  includes 3  -1      true  1  2  NaN  includes NaN      true   so something like  const array    1  3   if   array includes 2       array push 2     note the browser compatibility at the bottom of the page  however

User · Answer

If you use Lodash  take a look at   union function   let items       items     union  item   items

User · Answer

I guess ES6 has set data structure  which you can use for unique entries

User · Answer

Your logic is saying   if this item exists already  then add it   It should be the opposite of that   Change it to     if  this items indexOf item     -1        this items push item

[javascript] Array.push() and unique items

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