closure

app.html

    <style type="text/css">
        .red .x-progress-bar{
            background: palevioletred none;
        }
        .x-progress.red {
            border-color: #D3279C;
        }
    </style>

closure.js

var progressRenderer = (function(){
    var b = Ext.create('Ext.ProgressBar', {
         value: tmpValue,
         text: tmpText
    });
    if(color)b.setUI(color);
    return function() {
        return Ext.DomHelper.markup(b.getRenderTree());
    }
})(tmpValue, tmpText, color);
return progressRenderer(tmpValue, tmpText, color);

EXTJS 4 progress bar change background color