function hideAllLayers()<br />{<br /> forEach(document.layers, function(layer) {<br /> layer.visible = false;<br /> });<br />}<br /><br />function showAllLayers()<br />{<br /> forEach(document.layers, function(layer) {<br /> layer.visible = true;<br /> }); <br />}<br /><br />function forEach(collection, fn)<br />{<br /> var n = collection.length;<br /> for(var i=0; i<n; ++i)<br /> {<br /> fn(collection);<br /> }<br />}