  We investigate the $(\pi^0,\eta,\eta')\to\gamma^*\gamma$ transitions both for
the spacelike region and the timelike region using the light-front quark model
(LFQM). In particular, we present the new direct method to explore the timelike
region without resorting to mere analytic continuation from the spacelike
region to the timelike region. Our direct calculation in timelike region shows
the complete agreement not only with the analytic continuation result from the
spacelike region but also with the result from the dispersion relation between
the real and imaginary parts of the form factor. For the low energy regime, we
compare our LFQM results of the transition form factors (TFFs) for the low
timelike momentum transfer region and the slope parameters at $q^2=0$ with the
recent experimental data from the Dalitz decays of $(\pi^0,\eta,\eta')$. For
the high energy regime, we incorporate the QCD factorization in our LFQM to
examine the asymptotic behavior of TFFs both for the spacelike region and the
timelike region. We compare our results with the available experimental data.
