name: duk_require_function

proto: |
  void duk_require_function(duk_context *ctx, duk_idx_t idx);

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

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

  <div class="note">
  There is no "get" primitive (<code>duk_get_function()</code>) because there's
  no useful C return value for an arbitrary function.
  </div>

example: |
  duk_require_function(ctx, -3);

tags:
  - stack

introduced: 1.4.0