How to use Google Apps Script on any/all Spreadsheets? -

i trying implement spreadsheet app using google apps script. have several issue not mach requirements. have looked in these issues , unsuccessful find answers or better alternative ways implement functionality.

requirements:

write manageable testable code
not download script each spreadsheet somehow when install once can use on spreadsheet in drive.

1,2 problems faced.

the google apps script ide seems have difficulty in handling large code base (i mean not keep code managing , handle growth of code)
this major problem (not matching requirement)

let's create script spreadsheet , deploy , can install script on other script , execute it. has done each , every spreadsheet. installed script not in script manager used in spreadsheets without installing script form gallery every time.

and when create project of spreadsheets directly on google drive. since not allocated particular spreadsheet not allow me select dive (from script manager) , load script spreadsheet wish, , run/debug it.

i not hoping better solution above issue 1.

but issue no. 2 is burning one, can addressed match requirement?

if requirement can not achieved form google apps script, have go alternative.

alternatives thought far:

i thought desktop application can give spreadsheet url , give authentication information , using spreadsheet api necessary manipulations form desktop application. dummy est approach not user friendly.
go google app, can log in using g mail authentication , after giving spreadsheet url using spreadsheet api necessary manipulations. not sure authentication process google app , possibility of access permission drive.
final crome app, crome provided necessary authentication access given spreadsheet url , necessary manipulations spreadsheet.

which of options preferred, or there better solution matches requirement stated above?

the definition of "large code base" subjective, project several hundred lines of code can benefit organization. in ide have 2 primary tools available organize code; files , libraries.

this answer collection of links other answers, within number of topic areas should address concerns you've expressed.

code organization & libraries

a script project can have multiple files, of type "gs" (script) or "html". namespace extends across script files in project. separating methods files simple way organize code within project (for instance, place tests in 1 file separate production code), although little reusability across projects.

libraries projects published enable other projects incorporate capabilities without requiring them copy actual code. have @ notable script libraries start. libraries take name space library name - instance, have library of utilities related input & output of csv files, (cleverly) named csvutils. methods in library accessed csvutils.example(), , supported auto-complete feature. libraries support limited subset of jsdoc, , when published provide link generated documentation.

editor screen shot