se((x + 1, x > 0), (x, True)), sin(x)])
    >>> A = MatrixSymbol('A', 3, 1)
    >>> print(jscode(mat, A))
    A[0] = Math.pow(x, 2);
    if (x > 0) {
       A[1] = x + 1;
    }
    else {
       A[1] = x;
    }
    A[2] = Math.sin(x);
    N)