Chemical reaction calculator
This is a fundamentally very difficult question. Your example of of $\ce{HClO + NaOH}$ hides several assumptions, e.g., time frame and aqueous solution, which really means some number of $\ce{HClO}$, some number of $\ce{NaOH}$, and presumably a huge number of $\ce{H2O}$. When mixing all three components a wide variety of reactions take place, e.g., disproportionation of water ($\ce{H2O + H2O -&gt; H3O^{+} + OH^{-}}$), solvation of $\ce{NaOH}$ etc.

In general, a full exploration of all possible reactions and their barriers have to be assessed in order to make a prediction. For instance, $\ce{HClO + H2O -&gt; HCl + O2H2}$ is a possible reaction, or $\ce{NaOH + 2 HClO -&gt; NaCl + H2O2}$ even in the absence of extra water. The number of possible recombinations of the input materials generally increases exponentially with the number of atoms (e.g., the number of possible isomers of an n-alkane).