function filter_array(test_array) {  
    var index = -1,  
        arr_length = test_array ? test_array.length : 0,  
        resIndex = -1,  
        result = [];  
  
    while (++index < arr_length) {  
        var value = test_array[index];  
  
        if (value) {  
            result[++resIndex] = value;  
        }  
    }  
  
    return result;  
}  
console.log(filter_array([NaN, 0, 15, false, -22, '',undefined, 47, null]));