Names

Common naming practices.

Variables

Single Letter

i index
j secondary index
_ discarded value
x argument, variable
f, F function
T type
N number (integer)
C constant, coefficient
Q, Z effectiveness, goal

Several Letters

id index
rg regex pattern
no error object
ok success object
i, rq request object
o, rs response object

Entities

file-name.ext file name (kebab-case)
items/1 REST resource (plural)
/fonts/ folder name (plural)
CONST_NAME constant (UPPERCASE)
A Title title (Title Case)
MyClass class, module (PascalCase)
someFunc() function (camelCase)
_field private (but i don't like it)
IName interface (only methods, multiple inheritance)
AName, BaseName abstract (only signatures, single inheritance, prefixing is optional)
trackPlay register an event listener
isPlay bool, checker function
onPlay event handler
rgMail regex for email validation
objRef object reference
imgUrl image Url
valueChange$, newValue$ Event, Observable, Subject (JavaScript)

Placeholders (docs, especially for command line tools)

<N> number
<I> index, integer
<A> alphabetical, character, symbol
<S> string
<T> type
<?> bool
<@> url/file/reference
<*> all
[...] optional
<[T]> list of type T
<{S:N}> dictionary with string keys and number values
<name> variable (specified via monospace style in the descriptive text if is not obvious)

To-Do Lists

+ task done
- task to do
% task blocked
* task special: incomplete or demands attention (the more asterisks, the more important)
? task needs discussion
! task proposal, idea