per.mozilla.org/en-US/docs/Web/API/StorageEstimate">https://developer.mozilla.org/en-US/docs/Web/API/StorageEstimate</a></p></div></li></ul></div><h3 class="section">Fields</h3><div class="fields"><div class="field "><a name="usage"></a><h3 class="anchor"><code><span class="label label-meta label-meta-optional" title="Marks the field of a structure as optional.">@:optional</span><span class="label label-optional">optional</span><a href="#usage"><span class="identifier">usage</span></a>:<a class="type" title