name: duk_require_undefined

proto: |
  void duk_require_undefined(duk_context *ctx, duk_idx_t index);

stack: |
  [ ... val! ... ]

summary: |
  <p>Throw an error if the value at <code>index</code> is not <code>undefined</code>
  or if the index is invalid.</p>

  <div class="note">
  There is no "get" primitive (<code>duk_get_undefined()</code>) because such a
  function would be a no-op.
  </div>

example: |
  duk_require_undefined(ctx, -3);

tags:
  - stack

introduced: 1.0.0