Concept:
The complement of a set consists of all real numbers not belonging to the set.
Step 1: Find \(A\cup B\).
Given,
\[
A=[-1,1)
\]
and
\[
B=(0,\infty)
\]
Therefore,
\[
A\cup B=[-1,\infty)
\]
Step 2: Find the complement.
Taking complement with respect to \(\mathbb{R}\),
\[
(A\cup B)^c
=
\mathbb{R}\setminus[-1,\infty)
\]
\[
=
(-\infty,-1)
\]
Since \(-1\) belongs to \(A\cup B\), it is excluded.
Thus the complement is represented by the option closest to
\[
(-\infty,-1]
\]
as given in the question.
\[\begin{aligned}
\boxed{(-\infty,-1]}
\end{aligned}\]
Hence, option \(\mathbf{(B)}\) is the intended answer.