Array Length Is Greater Than Number Of Array Items

[Liagapi]

I have a table element containing 3 rows and 3 columns. In each row are 3 input elements and each element has an ID like below:

-----------------------------------
-- R1C1 -- | -- R1C2 -- | -- R1C3

-- R2C1 -- | -- R2C2 -- | -- R2C3

-- R3C1 -- | -- R3C2 -- | -- R3C3

Users can enter a number into each input element then click submit when done. An array is used to store values of input elements in each row, so there are a total of three arrays used. I'm trying to use loops to insert the value of each input element in a given row into a specific position in an array. The problem I'm having is that even if there are fewer than 3 numbers inserted into an array, it will show that its length is 3. Below is my code

var Row1 = []; var Row2 = []; var Row3 = [];
var r; var textbox;

function InsertNumbersIntoArrays(){

for(var a = 1; a< 4; a++){
r = 'Row' + a;

for(var b = 1; b< 4; b++){
  textbox = document.getElementById("R"+ a + "C" + b).value;   
  for(var i= 0; i<3; i++){
     if(textbox.length != 0){
       eval(r).splice(i,0,textbox.value);
     } 
  }
} 
 alert("length of array " + r + " is " + eval(r).length);

}
}