How to get first N number of elements from an array

Question

I am working with Javascript ES6   FaceBook react and trying to get the first 3 elements of an array that varies in size  I would like do the equivalent of Linq take n    In my Jsx file I have  the following   var items   list map i   gt      return        lt myview item  i  key  i id    gt             Then to get the first 3 items I tried    var map   new Map list       map size   3      var items   map i   gt          return   lt SpotlightLandingGlobalInboxItem item  i  key  i id    gt              This didn t work  as map doesn t have a set function   Can you please help

User · Answer

To get the first n elements of an array  use  array slice 0  n

User · Answer

arr length   n  This might be surprising but length property of an array is not only used to get number of array elements but it s also writable and can be used to set array s length MDN link  This will mutate the array  If you don t care about immutability or don t want to allocate memory i e  for a game this will be the fastest way  to empty an array arr length   0

User · Answer

Do not try doing that using a map function  Map function should be used to map values from one thing to other  When the number of input and output match   In this case use filter function which is also available on the array  Filter function is used when you want to selectively take values maching certain criteria  Then you can write your code like  var items   list               filter  i  index    gt   index  lt  3                 map  i  index    gt                       return                         lt myview item  i  key  i id    gt

User · Answer

With LInQer you can do  Enumerable from list  take 3  toArray

User · Answer

With lodash  take function  you can achieve this by following    take  1  2  3         gt   1      take  1  2  3   2        gt   1  2      take  1  2  3   5        gt   1  2  3      take  1  2  3   0        gt

User · Answer

Using a simple example  var letters     quot a quot    quot b quot    quot c quot    quot d quot    var letters 02   letters slice 0  2   console log letters 02    Output    quot a quot    quot b quot    var letters 12   letters slice 1  2   console log letters 12    Output    quot b quot    Note  slice provides only a shallow copy and DOES NOT modify the original array

User · Answer

I believe what you re looking for is          inside the render   function  var size   3  var items   list slice 0  size  map i   gt        return  lt myview item  i  key  i id    gt     return      lt div gt       items     lt  div gt

User · Answer

You can filter using index of array     x000D   x000D  var months     Jan    March    April    June    x000D  months   months filter  month idx    gt  idx  lt  2  x000D  console log months   x000D   x000D   x000D

User · Answer

The following worked for me   array slice  where to start deleting  array length     Here is an example  var fruits     Banana    Orange    Apple    Mango    fruits slice 2  fruits length     Banana Orange  - gt These first two we get as resultant

[javascript] How to get first N number of elements from an array

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