JavaScript Array to Set

Question

MSDN references JavaScript s Set collection abstraction  I ve got an array of objects that I d like to convert to a set so that I am able to remove   delete    various elements by name   var array          name   malcom   dogType   four-legged         name   peabody   dogType   three-legged         name   pablo   dogType   two-legged        How do I convert this array to a set  More specifically  is it possible to do this without iterating over the above array  The documentation is relatively lacking  sufficient for instantiated sets  not for conversions - if possible    I may also be thinking of the conversion to a Map  for removal by key  What I am trying to accomplish is an iterable collection that can be accessed or modified via accessing the elements primarily via a key  as opposed to index     Conversion from an array to the other being the ultimate goal

User · Answer

By definition  A Set is a collection of values  where each value may occur only once   So  if your array has repeated values then only one value among the repeated values will be added to your Set   var arr    1  2  3   var set   new Set arr   console log set       1 2 3    var arr    1  2  1   var set   new Set arr   console log set       1 2    So  do not convert to set if you have repeated values in your array

User · Answer

What levi said about passing it into the constructor is correct  but you could also use an object   I think what Veverke is trying to say is that you could easily use the delete keyword on an object to achieve the same effect   I think you re confused by the terminology  properties are components of the object that you can use as named indices  if you want to think of it that way    Try something like this   var obj          bob    dole        mr     peabody        darkwing    duck       Then  you could just do this   delete obj  bob      The structure of the object would then be this          mr     peabody        darkwing    duck      Which has the same effect

User · Answer

If you start out with   let array          name   malcom   dogType   four-legged         name   peabody   dogType   three-legged         name   pablo   dogType   two-legged        And you want a set of  say  names  you would do   let namesSet   new Set array map item   gt  item name

User · Answer

Just pass the array to the Set constructor  The Set constructor accepts an iterable parameter  The Array object implements the iterable protocol  so its a valid parameter    x000D   x000D  var arr    55  44  65   x000D  var set   new Set arr   x000D  console log set size     arr length   x000D  console log set has 65    x000D   x000D   x000D    See here

[javascript] JavaScript Array to Set

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