Plotting Basis Order function

If you want to use Mathematica as it is designed to generate the Lagrange basis as a list of polynomials, then use InterpolatingPolynomial:

lBasis[nodes_, x_] := Table[
  InterpolatingPolynomial[
   Transpose@{nodes, UnitVector[Length@nodes, k]}, x],
  {k, Length@nodes}]

To plot them:

xj = {0, 2, 3, 7, 10, 11};
Plot[lBasis[xj, x] // Evaluate, {x, Min[xj], Max[xj]},
 Epilog -> {Red, Point@Thread[{xj, 1}], Point@Thread[{xj, 0}]},
 GridLines -> {xj, {1}}]

To get the same thing from my comment, fix the typo in the comment and use Table to list the basis:

L[i_, xj_, x_] := (* i-th Lagrange basis function *)
 Fold[Times, (x - #)/(xj[[i]] - #) &@Drop[xj, {i}]];
lBasis[nodes_, x_] := Table[L[k, nodes, x], {k, Length@nodes}]

If you want to write something like a C program as an exercise and not avoid the for loop, then maybe someone else can help with that.