JavaScript: getVariable GetExtension

html = "w1=0.23&w2=0.29&error=0";

error = getVariable(html,"error");

function getVariable(html, variable)
{
    if ( html.indexOf(variable) < 0 ) return "-1";
        
    var resultado = "-1";
    
    var parts = html.split("&");
    var cant = parts.length;

    for ( i = 0; i < cant; i++)
    {
        str = parts[i];
        if ( str.indexOf(variable) != -1 )  //parts[i] == variable )
        {    
            var word = str.split("=");
            resultado = word[1];
            //alert("encontre");
            break;
        }
    }
    
    return resultado;
}

function GetExtension(Filename) {
    var I = Filename.lastIndexOf(".");
    return (I > -1) ? Filename.substring(I + 1, Filename.length) : "";
}