old_contents: // PRETTYPRINT
  
  // Print concentric rectangular pattern in a 2d matrix.
  // Let us show you some examples to clarify what we mean.
  
  // Example 1:
  
  // Input: A = 4.
  // Output:
  
  // 4 4 4 4 4 4 4
  // 4 3 3 3 3 3 4
  // 4 3 2 2 2 3 4
  // 4 3 2 1 2 3 4
  // 4 3 2 2 2 3 4
  // 4 3 3 3 3 3 4
  // 4 4 4 4 4 4 4
  // Example 2:
  
  // Input: A = 3.
  // Output:
  
  // 3 3 3 3 3
  // 3 2 2 2 3
  // 3 2 1 2 3
  // 3 2 2 2 3
  // 3 3 3 3 3
  // The outermost rectangle is formed by A, then the next outermost is formed by A-1 and so on.
  
  // You will be given A as an argument to the function you need to implement, and you need to return a 2D array.
  
  function prettyPrint(A){
        var matrix = [],
            x = 2*A-2,
            y = A;
  
  
        function genMat(k,n,m){
            var x = k,
                y = n;
            for(var i=k; i<2*A-1;i++){
                for(var j=k; j<2*A-1; j++){
                    if( i===x||j===x||i===y||j===y){
                        if(matrix[i][j] === 0) matrix[i][j] = m;
                    }
                }
            }
        }
  
        for(var i=0;i<2*A-1;i++){ // create empty matrix
            matrix[i] = [];
            for(var j=0;j<2*A-1;j++){
                matrix[i][j]=0;
            }
        }
        for(i=0; i<A; i++){
            genMat(i,x,y);  // Construction of outer box
            x--;
            y--;
        }
        return matrix
  }
  
  console.log( prettyPrint(3) )
  
new_contents: // PRETTYPRINT
  
  // Print concentric rectangular pattern in a 2d matrix.
  // Let us show you some examples to clarify what we mean.
  
  // Example 1:
  
  // Input: A = 4.
  // Output:
  
  // 4 4 4 4 4 4 4
  // 4 3 3 3 3 3 4
  // 4 3 2 2 2 3 4
  // 4 3 2 1 2 3 4
  // 4 3 2 2 2 3 4
  // 4 3 3 3 3 3 4
  // 4 4 4 4 4 4 4
  // Example 2:
  
  // Input: A = 3.
  // Output:
  
  // 3 3 3 3 3
  // 3 2 2 2 3
  // 3 2 1 2 3
  // 3 2 2 2 3
  // 3 3 3 3 3
  // The outermost rectangle is formed by A, then the next outermost is formed by A-1 and so on.
  
  // You will be given A as an argument to the function you need to implement, and you need to return a 2D array.
  
  function prettyPrint(A){
        var matrix = [],
            x = 2*A-2,
            y = A;
  
  
        function genMat(k,n,m){
            var x = k,
                y = n;
            for(var i=k; i<2*A-1; i++){
                for(var j=k; j<2*A-1; j++){
                    if( i===x||j===x||i===y||j===y ){
                        if(matrix[i][j] === 0) matrix[i][j] = m;
                    }
                }
            }
        }
  
        for(var i=0; i<2*A-1; i++){ // create empty matrix
            matrix[i] = [];
            for(var j=0;j<2*A-1;j++){
                matrix[i][j]=0;
            }
        }
        for(i=0; i<A; i++){
            genMat(i,x,y);  // Construction of outer box
            x--;
            y--;
        }
        return matrix
  }
  
  console.log( prettyPrint(3) )
  
subject: edit solution