External module "iter/unique-by/docs/types/index.d"

Export assignment iterUniqueBy

• iterUniqueBy(iterator: Iterator, predicate: Predicate, thisArg?: any): Iterator

• Returns an iterator which returns unique values according to a predicate function.

  Notes

  • A returned iterator internally buffers unique values and, thus, has O(N) memory requirements.
  • A predicate function is invoked for each iterated value against each value in an internal buffer consisting of previously identified unique values. Thus, as the number of unique values grows, so, too, does the number of predicate function invocations per iterated value.
  • An iterated value is considered "unique" if the predicate function returns truthy values for all comparisons of the iterated value with each value in the internal buffer.
  • If an environment supports Symbol.iterator and a provided iterator is iterable, the returned iterator is iterable.

  Parameters

  • iterator: Iterator

    input iterator

  • predicate: Predicate

    predicate function

  • Optional thisArg: any

    predicate function execution context

  Returns Iterator

  iterator

  Example

  var array2iterator = require( `@stdlib/array/to-iterator` );
  
  function predicate( a, b ) {
      return ( a !== b );
  }
  
  var iter = iterUniqueBy( array2iterator( [ 1, 2, 1, 2, 4 ] ), predicate );
  
  var v = iter.next().value;
  // returns 1
  
  v = iter.next().value;
  // returns 2
  
  v = iter.next().value;
  // returns 4
  
  var bool = iter.next().done;
  // returns true