proposal-iterator-includes/spec.emu at main · tc39/proposal-iterator-includes · GitHub

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<!doctype html>
<meta charset="utf8">
<pre class="metadata">
title: Iterator Includes
status: proposal
stage: 2.7
contributors: Michael Ficarra
location: https://tc39.es/proposal-iterator-includes/
copyright: false
</pre>

<emu-clause id="sec-iterator.prototype.includes">
  <h1>Iterator.prototype.includes ( _searchElement_ [ , _skippedElements_ ] )</h1>
  <emu-alg>
    1. Let _O_ be the *this* value.
    1. If _O_ is not an Object, throw a *TypeError* exception.
    1. Let _iterated_ be the Iterator Record { [[Iterator]]: _O_, [[NextMethod]]: *undefined*, [[Done]]: *false* }.
    1. If _skippedElements_ is *undefined*, then
      1. Let _toSkip_ be 0.
    1. Else,
      1. If _skippedElements_ is not one of *+∞<sub>𝔽</sub>*, *-∞<sub>𝔽</sub>*, or an integral Number, then
        1. Let _error_ be ThrowCompletion(a newly created *TypeError* object).
        1. Return ? IteratorClose(_iterated_, _error_).
      1. Let _toSkip_ be the extended mathematical value of _skippedElements_.
    1. If _toSkip_ &lt; 0, then
      1. Let _error_ be ThrowCompletion(a newly created *RangeError* object).
      1. Return ? IteratorClose(_iterated_, _error_).
    1. Let _skipped_ be 0.
    1. Set _iterated_ to ? GetIteratorDirect(_O_).
    1. Repeat,
      1. Let _value_ be ? IteratorStepValue(_iterated_).
      1. If _value_ is ~done~, return *false*.
      1. If _skipped_ &lt; _toSkip_, then
        1. Set _skipped_ to _skipped_ + 1.
      1. Else if SameValueZero(_value_, _searchElement_) is *true*, then
        1. Return ? IteratorClose(_iterated_, NormalCompletion(*true*)).
  </emu-alg>
</emu-clause>