function checkExtension(objFile, arrLst) 
{
    var retVal = false;
    var ext = getFileExtension(objFile.value);
    for(i=0;i<arrLst.length;i++)  
    {
        var ptrnImgExt= new RegExp(ext,'i');
        if(arrLst[i].search(ptrnImgExt) > -1)
        {
            retVal = true;
            break;
         }
    };
    return retVal;
}
    
function getFileExtension(objFileName)
{
    var ext = objFileName;
    lindx = ext.lastIndexOf('.');
    if (lindx > -1)
    {
        ext = ext.substring(lindx);
        return ext;
    }
    else
    {
        return '';
    }
}

function uploadImage(hdnFld, hfVal, formId, objFile, arrLst, errorVal)
{
    //console.log(hdnFld + ' -- ' + hfVal + ' -- ' + formId + ' -- ' + objFile + ' -- ' + arrLst);
    //hdnFld = 'hdnUpload'
    //hfVal = 'alternateimage'/'mainimage'
    //formId = 'form1'
    var hdn;
    var frm;
    if(document.getElementById(hdnFld))
    {
        hdn = document.getElementById(hdnFld);
    }
    else
    {
        hdn = document.getElementsByName(hdnFld)[0];   
    }
    if(!hdn) return;
    if(document.getElementById(hdnFld))
    {
        frm = document.getElementById(formId);
    }
    else
    {
        frm = document.getElementsByName(formId)[0];   
    }
    if(!frm) return;
    if(checkExtension(objFile, arrLst))
    { 
        hdn.value=hfVal;
        frm.submit();
    }
    else
    {
        hdn.value=errorVal;
        objFile.value='';
        objFile.disabled = true;
        frm.submit();
    }
}