What is the JavaScript equivalent to a C# HashSet?

Question

I have a list of a few thousand integer keys. The only thing I need to do with this list is say whether or not a given value is in the list.

For C# I would use a

Answer 1

Under the hood, the JavaScript Object is implemented with a hash table. So, your Key:Value pair would be (your integer):true

A constant-time lookup function could be implemented as:

var hash = {
  1:true,
  2:true,
  7:true
  //etc...
};

var checkValue = function(value){
  return hash[value] === true;
};


checkValue(7); // => true
checkValue(3); // => false