As

Co-relator

Equivalence

as ADJ as = aussi ADJ que

as ADV as = aussi ADV que

as many Ns as = autant de Ns que

as few Ns as = aussi peu de Ns que

as much N as = autant de N que

as little N as = aussi peu de N que

The first correlator can be replaced with so, though this is very marked (and rare).

just as ADJ as. ("But elder brother was just as late (last night) as I was (tonight), and you hardly said a word to him.")

Will shopping malls be just as packed as ever?

Rules

• as is not followed immediately by comparatives (e.g. older, more involved, etc.) because "as" is used in comparisons of (non-)equivalence
  whereas comparatives are used in comparisons of superiority/inferiority with than.
• as is not generally used with superlatives. The single exception I know is "best" (see expressions below).

Non-equivalence / proportion

That's not as funny as when...

We could do with half as many wisecracks.

half as much effort (see contexts: [1])

twice as many people

twice as much traffic

three times as many stalled tractors as last time

Reason

As I was on call anyway, I decided to go in to work. --> Comme j'étais d'astreinte de toutes façons, j'ai décidé d'aller bosser.

inasmuch as: dans la mésure où, étant donné que, ...

insofar as: dans la mésure où, pour autant que, dès lors que...

Marker of simultaneity

As I was parking, I realized I had forgotten my mask. En me garant, je me suis rendu compte que j'avais oublié une masque.

Expressions

as far as [X] goes, ... -- Quant à [X], ...

as far as I know -- pour autant que je sache, à ma connaissance

as far as I can tell -- d'après ce que je comprends/vois

as best (as) I can tell -- d'après ce que je comprends/vois ("as well as I can tell" would follow grammar rules better, but real word use and grammatical consistency are two different things. :D )

as far as I'm concerned -- Quant à moi

as you (wish / like) -- comme tu veux

as you see fit -- comme tu le sens

as much as I would like to...

as for: -- quant à

try as I might, I couldn't [X] -- J'ai beau essayer, mais je n'arrivais pas à [X].

as soon as possible -- yesterday, usually.  :)