@MartinSleziak There's still room for some small improvement for that script, we can edit it so that it deletes every "\right", "\left", "\limits" and "\displaystyle" since those aren't supported in Approach0 yet, and also it should replace "dfrac" or "tfrac" with "frac".
I was able to implement this last feature, but I don't know how to do it correctly for "\right" and others. Here's the updated version:
@Workaholic IIRC Approach0 does not differentiate between frac and dfrac, and I guess that other things such as \limits probably do not influence search either.
@WeiZhong says that one of the features that he wants to implement is "query expansion, e.g. \left| a + b \right| +==> | a + b|", I interpreted that as meaning that \left and \right do play a role in the search query but it doesn't seem to be the case here. So I'll let him clarify this :)