Change the visibility of layer by using variable i

问题:

This is my select option.

<select id="sel_dist" onChange="seldist();">
    <option value="layer1" selected=selected>None</option>
    <option value="layer2">1</option>
    <option value="layer3">2</option>
</select>

This is my layer in Openlayers

layer1 =  new OpenLayers.Layer.WMS("Map",serverWMS,
                                        {layers: 'test:Layer1',transparent: true},
                                        {isBaseLayer:false, visibility: false});

What i want to do is when i select option "Layer 1", layer 1 should be visible.

function seldist()
{
var layer_name=$("#sel_dist option:selected").val()
layer_name.setVisibility(true);
}

But when i use layer_name.setVisibilityit assumes 'layer_name' as layer name but i want to use it as variable only. Any help would be much appreciated.

回答1:

Edited:

eval(layer_name).setVisibility(true);