Javascript Array Multidimensional array initialize

let array1 = [ [ 1, 2, 3 ], // first row   
               [ 4, 5, 6 ] ]; // second row

let array2 = [ [ 1, 2 ], // first row      
               [ 3 ], // second row        
               [ 4, 5, 6 ] ]; // third row 

outputArray( "Values in array1 by row", array1 );
outputArray( "Values in array2 by row", array2 );

function outputArray( heading, theArray )
{
   console.log(heading);//w w  w  . jav  a 2  s  .  co m

   // iterates through the set of one-dimensional arrays
   for ( let i in theArray )                       
   {                                                  
      // iterates through the elements of each one-dimensional 
      // array
      for ( let j in theArray[ i ] )                
         console.log( theArray[ i ][ j ] + " " );
   }
}