s_">Reflect</span>.<span class="hljs-title function_">apply</span>(_set, retObj, [key, newValue]);
    }
    <span class="hljs-keyword">return</span> retObj;
}</code></pre></emu-import>
        </emu-clause>

        <emu-clause id="Map.prototype.mapKeys">
            <h1><span class="secnum">3.2</span> Map.prototype.mapKeys( <var>callbackfn</var>, [ <var>thisArg</var> ] )</h1>
            <emu-import href="./map/prototype-map-keys.html"><emu-note type="editor"><span class="note">Editor's Note</span><div cl