Rules

Rules support matrix by techno

This matrix lists all the rules identified as implementable within the standard creedengo plugin.

Some are applicable for different technologies.

✅ Rule included in current version of creedengo
🚧 Rule implementation in progress
🚀 Rule to implement
❓ Rule to analyze for applicability
🚫 Non applicable rule

Rule key Name Description Reference/Validation Java Php JS Python Rust C# HTML

Rule key	Name	Description	Reference/Validation	Java	Php	JS	Python	Rust	C#	HTML
CRJVM205	Force usage of FetchType LAZY for collections on JPA entities			🚧	❓	❓	❓	❓	❓	🚫
CRJVM206	Avoid N+1 selects problem			🚧	❓	❓	❓	❓	❓	🚫
CRJVM207	Customer data must have end-of-life information			🚧	❓	❓	❓	❓	❓	❓
CRJVM???	Persistence Java : Avoid Joints on non indexed columns			🚧	❓	❓	❓	❓	❓	🚫
GCI1	Calling a Spring repository inside a loop or a stream	The use of Spring repository in a loop or a stream induces unnecessary calculations by the CPU and therefore superfluous energy consumption.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI2	Multiple if-else statements	Using too many conditional if-else statements will impact performance since JVM will have to compare the conditions. Prefer using a switch statement instead of multiple if-else if possible, or refactor your code to reduce conditonnal statements on the same variable. Switch statement has a performance advantage over if – else.		✅	✅	🚀	✅	🚀	🚀	🚫
GCI3	Getting the size of the collection in the loop	When iterating over any collection, fetch the size of the collection in advance to avoid fetching it on each iteration, this saves CPU cycles, and therefore consumes less power.		✅	✅	🚀	🚫	🚀	🚫	🚫
GCI4	Use global variables	When using a global variable, the interpretation engine must check: 1) that it exists in the current scope, in the one above, etc. ; 2) the variable has a value; 3) … To avoid all these checks, it is often possible to pass the useful variables as arguments of routines, making them local. This process saves computational time (CPU cycles).	cnumr best practices (3rd edition) BP_050 (no longer exists in edition 4)	🚫	✅	🚀	✅	🚀	🚫	🚫
GCI5	Usage of preparedStatement instead of Statement	SQL will only commit the query once, whereas if you used only one statement, it would commit the query every time and thus induce unnecessary calculations by the CPU and therefore superfluous energy consumption.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI7	Rewrite native getter/setters	Overloading them lengthens the compilation and execution times of these methods, which are usually much better optimized by the language than by the developer.	cnumr best practices (3rd edition) BP_062 (no longer exists in edition 4)	🚫	🚫	🚀	✅	🚀	🚫	🚫
GCI9	Importing everything from library should be avoided	ESLint key : @ecocode/no-import-all-from-library /// type : Common		❓	❓	✅	❓	❓	❓	🚫
GCI10	Use unoptimized vector images	Less heavy SVG images using less bandwidth	cnumr best practices (3rd edition) BP_036	🚧	🚀	🚀	✅	🚀	🚫	❓
GCI11	Multiple access of same DOM element should be limited	ESLint key : @ecocode/no-multiple-access-dom-element /// type : Front-end		🚫	❓	✅	🚫	🚫	❓	🚫
GCI12	Multiple style changes should be batched	ESLint key : @ecocode/no-multiple-style-changes /// type : Front-end		🚫	❓	✅	🚫	🚫	❓	🚫
GCI13	API collections should be preferred with pagination	ESLint key : @ecocode/prefer-collections-with-pagination /// type : Back-end		❓	❓	✅	❓	❓	❓	🚫
GCI22	The use of methods for basic operations	Using methods for basic operations consumes additional system resources. The interpreter must in effect and solve the objects and then the methods, just to carry out these simple operations of the language.	cnumr best practices (3rd edition) BP_048 (no longer exists in edition 4)	🚫	🚫	🚀	🚀	🚀	🚫	🚫
GCI24	Returned SQL results should be limited	ESLint key : @ecocode/limit-db-query-results /// type : Back-end		🚧	🚀	✅	🚀	🚀	🚀	🚫
GCI25	Images should not have an empty source attribute	ESLint key : @ecocode/no-empty-image-src-attribute /// type : Front-end		❓	❓	✅	❓	❓	❓	🚀
GCI26	Shorthand CSS notations should be used to reduce stylesheets size	ESLint key : @ecocode/prefer-shorthand-css-notations /// type : Front-end		❓	❓	✅	❓	❓	❓	🚫
GCI27	Usage of system.arraycopy to copy arrays	Programs spend most of the time in loops. These can be resource consuming, especially when they integrate heavy processing (IO access). Moreover, the size of the data and processing inside the loops will not allow full use of hardware mechanisms such as the cache or compiler optimization mechanisms.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI28	Optimize read file exceptions			✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI29	CSS animations should be avoided	ESLint key : @ecocode/avoid-css-animations /// type : Front-end		❓	❓	✅	❓	❓	❓	🚫
GCI30	Print stylesheet should be provided	ESLint key : @ecocode/provide-print-css /// type : Front-end		❓	❓	✅	❓	❓	❓	🚫
GCI31	Lighter formats should be used for image files	ESLint key : … /// type : …		🚧	❓	✅	❓	❓	❓	🚀
GCI32	Initialize builder/buffer with the appropriate size	If you know in advance how many characters would be appended, initialize builder/buffer with the appropriate size. They will thus never have to be resized. This saves CPU cycles and therefore consumes less energy.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI35	Using try…catch calls (on File Not Found error)	When an exception is thrown, a variable (the exception itself) is created in the catch block and destroyed at the end of the block. Creating this variable and destroying it consumes CPU cycles and RAM unnecessarily. That is why it is important not to use this construction and to prefer, as much as possible, a logical test. This new rule replace old GCI34 only for a particular use case (FileNotFoundException)	cnumr best practices (3rd edition) BP_047 (no longer exists in edition 4)	🚫	✅	🚀	✅	🚀	🚫	🚫
GCI36	Autoplay should be avoided for video and audio content	Autoplaying media consumes unnecessary energy, especially when users might not be actively engaging with the content.	cnumr best practices BP_4003	🚫	🚫	✅	🚫	🚫	🚫	🚧
GCI66	Use single quote (') instead of quotation mark (")	The shape using the quotation marks allows the developer to insert variables that will be substituted at run time. But if the string does not have a variable, use quotes instead. Thus, language will not look for variables to subtituture, which will reduce the consumption of CPU cycles.	cnumr best practices (3rd edition) BP_066 (no longer exists in edition 4)	🚀	✅	🚀	🚫	🚀	🚫	🚫
GCI67	Use the $i++ variable during an iteration	The $i form has the disadvantage of generating a tem-porary variable during incrementation, which is not the case with the $i form.	cnumr best practices (3rd edition) BP_067 (no longer exists in edition 4)	✅	✅	🚀	🚫	🚫	🚫	🚫
GCI69	Calling a loop invariant function in a loop condition	Avoid calling loop invariant functions in loop conditions.	cnumr best practices (3rd edition) BP_069 (no longer exists in edition 4)	✅	✅	🚀	🚫	🚀	✅	🚫
GCI72	Perform an SQL query inside a loop	Servers are optimized to process multiple selections, insertions, or changes in a single query or transaction. consume CPU cycles, RAM, and bandwidth unnecessarily.	cnumr best practices (3rd edition) BP_072	✅	✅	🚀	✅	🚀	✅	🚫
GCI74	Write SELECT * FROM	The database server must resolve the fields based on the schema. If you are familiar with the diagram, it is strongly recommended to name the fields.	cnumr best practices (3rd edition) BP_074 (no longer exists in edition 4)	✅	✅	🚀	✅	🚀	🚀	🚫
GCI75	Don’t concatenate strings in loops	Avoid repeated string allocations and consider using a StringBuilder instead.		🚫	❓	❓	❓	❓	✅	🚫
GCI76	Usage of static collections	Avoid usage of static collections. If you want to use static collections make them final and create for example a singleton if needed containing the collections. The static fields are more complicated for the Garbage Collector to manage and can lead to memory leaks.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI77	Usage Pattern.compile() in a non-static context	Avoid using Pattern.compile() in a non-static context. This operation requires a non negligible amount of computational power, Using a single match saves CPU cycles and RAM consumption.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI78	Const parameter in batch update	Don’t set const parameter in batch update ⇒ Put its in query. Creating this parameter and destroying it consumes CPU cycles and RAM unnecessarily.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI79	Free resources	try-with-resources Statement needs to be implemented for any object that implements the AutoCloseable interface, it save computer resources.		✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI81	Specify struct layouts	When possible, specify struct layouts to optimize their memory footprint		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI82	Make variable constant	A variable is never reassigned and can be made constant		✅	🚀	🚀	🚀	🚀	✅	🚫
GCI83	Replace Enum ToString() with nameof	When no string format is applied, use nameof instead of ToString() for performance		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI84	Avoid async void methods	Use async Task methods instead, for performance, stability and testability		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI85	Make type sealed	Seal types that don’t need inheritance for performance reasons		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI86	GC.Collect should not be called	In most cases, the cost of calling GC.Collect far outweighs the benefits		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI87	Use collection indexer	Collection indexers should be used instead of Linq, when available		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI88	Dispose resource asynchronously	Resources that implement `IAsyncDisposable` should be disposed asynchronously		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI89	Avoid using function cache without limit	If a function has decorators without max size cache, the program will store unlimited data		❓	❓	❓	✅	❓	❓	❓
GCI90	Use `Cast` instead of `Select` to cast	`Cast` is optimized for this scenario and should be used		❓	❓	❓	❓	❓	✅	❓
GCI91	Use `Where` before `OrderBy`	Filter elements before sorting them for improved efficiency		❓	❓	❓	❓	❓	✅	❓
GCI92	Use string.Length instead of comparison with empty string	Comparing a string to an empty string is unnecessary and can be replaced by a call to `string.Length` which is more performant and more readable.		🚫	🚫	🚫	🚫	🚫	✅	🚫
GCI93	Return `Task` directly	Consider returning a `Task` directly instead of a single `await`		❓	❓	❓	❓	❓	✅	❓
GCI94	Use orElseGet instead of orElse	Parameter of orElse() is evaluated, even when having a non-empty Optional. Supplier method of orElseGet passed as an argument is only executed when an Optional value isn’t present. Therefore, using orElseGet() will save computing time.	Optimized use of Java Optional Else	✅	🚫	🚫	🚫	🚫	🚫	🚫
GCI203	Detect unoptimized file formats	When it is possible, to use svg format image over other image format		🚧	🚀	🚀	✅	🚀	🚀	🚫
GCI404	Avoid list comprehension in iterations	Use generator comprehension instead of list comprehension in for loop declaration		🚫	🚫	🚫	✅	🚫	🚫	🚫
GCI522	Sobriety: Brightness Override	To avoid draining the battery, iOS and Android devices adapt the brightness of the screen depending on the environment light.		🚫	🚫	✅	🚫	🚫	🚫	🚫
GCI523	Sobriety: Thrifty Geolocation (minTime)	High-precision geolocation typically requires more power from the device’s GPS hardware.		🚫	🚫	✅	🚫	🚫	🚫	🚫
GCI530	Sobriety: Torch Free	Turning on the torch mode programmatically must absolutely be avoided because the flashlight is one of the most energy-intensive component.		🚫	🚫	✅	🚫	🚫	🚫	🚫
	Use official social media sharing buttons	These JavaScript plugins are very resource-intensive: to work, they require a large number of requests and download heavy files. It is better to prefer direct links.	cnumr best practices (3rd edition) BP_019	🚫	🚫	🚀	🚫	🚫	🚫	🚀
	Non-grouped similar CSS declarations	When multiple Document Object Model (DOM) elements have common CSS properties, declare them together in the same style sheet. This method reduces the weight of CSS.	cnumr best practices (3rd edition) BP_025	🚫	🚫	🚧	🚫	🚫	🚫	🚫
	Non-standard fonts used	Prefer standard fonts, as they are already present on the user’s computer, so they do not need to download them. This saves bandwidth, while speeding up the display of the site.	cnumr best practices (3rd edition) BP_029	🚫	🚫	🚫	🚫	🚫	🚫	🚫
	Non-outsourced CSS and Javascript	If you include CSS or JavaScript code in the body of the HTML file, while the HTML file is used by several pages (or even the entire site), this code must be transferred for each page requested by the user, which increases the volume of data transmitted.	cnumr best practices (3rd edition) BP_032	🚫	🚫	🚀	🚫	🚫	🚫	🚀
	Resize images browser-side	Do not resize images using the HEIGHT and WIDTH attributes of the HTML code. This approach requires transferring these images to their original size, wasting bandwidth and CPU cycles.	cnumr best practices (3rd edition) BP_034	🚫	🚫	🚧	🚫	🚫	🚫	🚀
	Modify the DOM when traversing it	Modifying the DOM (Document Object Model) as you traverse it can lead to situations where the loop becomes very resource-intensive, especially CPU cycles.	cnumr best practices (3rd edition) BP_041	🚫	🚫	🚧	🚫	🚫	🚫	🚫
	Edit DOM elements to make it invisible	When an element of the Document Object Model (DOM) needs to be modified by several properties, each change in style or content will generate a repaint or reflow.	cnumr best practices (3rd edition) BP_042	🚫	🚫	🚀	🚫	🚫	🚫	🚫

CRJVM205

Force usage of FetchType LAZY for collections on JPA entities

🚧

❓

🚫

CRJVM206

Avoid N+1 selects problem

🚧

❓

🚫

CRJVM207

Customer data must have end-of-life information

🚧

❓

CRJVM???

Persistence Java : Avoid Joints on non indexed columns

🚧

❓

🚫

GCI1

Calling a Spring repository inside a loop or a stream

The use of Spring repository in a loop or a stream induces unnecessary calculations by the CPU and therefore superfluous energy consumption.

✅

🚫

GCI2

Multiple if-else statements

Using too many conditional if-else statements will impact performance since JVM will have to compare the conditions. Prefer using a switch statement instead of multiple if-else if possible, or refactor your code to reduce conditonnal statements on the same variable. Switch statement has a performance advantage over if – else.

✅

🚀

✅

🚀

🚫

GCI3

Getting the size of the collection in the loop

When iterating over any collection, fetch the size of the collection in advance to avoid fetching it on each iteration, this saves CPU cycles, and therefore consumes less power.

✅

🚀

🚫

🚀

🚫

GCI4

Use global variables

When using a global variable, the interpretation engine must check: 1) that it exists in the current scope, in the one above, etc. ; 2) the variable has a value; 3) … To avoid all these checks, it is often possible to pass the useful variables as arguments of routines, making them local. This process saves computational time (CPU cycles).

cnumr best practices (3rd edition) BP_050 (no longer exists in edition 4)

🚫

✅

🚀

✅

🚀

🚫

GCI5

Usage of preparedStatement instead of Statement

SQL will only commit the query once, whereas if you used only one statement, it would commit the query every time and thus induce unnecessary calculations by the CPU and therefore superfluous energy consumption.

✅

🚫

GCI7

Rewrite native getter/setters

Overloading them lengthens the compilation and execution times of these methods, which are usually much better optimized by the language than by the developer.

cnumr best practices (3rd edition) BP_062 (no longer exists in edition 4)

🚫

🚀

✅

🚀

🚫

GCI9

Importing everything from library should be avoided

ESLint key : @ecocode/no-import-all-from-library /// type : Common

❓

✅

❓

🚫

GCI10

Use unoptimized vector images

Less heavy SVG images using less bandwidth

cnumr best practices (3rd edition) BP_036

🚧

🚀

✅

🚀

🚫

❓

GCI11

Multiple access of same DOM element should be limited

ESLint key : @ecocode/no-multiple-access-dom-element /// type : Front-end

🚫

❓

✅

🚫

❓

🚫

GCI12

Multiple style changes should be batched

ESLint key : @ecocode/no-multiple-style-changes /// type : Front-end

🚫

❓

✅

🚫

❓

🚫

GCI13

API collections should be preferred with pagination

ESLint key : @ecocode/prefer-collections-with-pagination /// type : Back-end

❓

✅

❓

🚫

GCI22

The use of methods for basic operations

Using methods for basic operations consumes additional system resources. The interpreter must in effect and solve the objects and then the methods, just to carry out these simple operations of the language.

cnumr best practices (3rd edition) BP_048 (no longer exists in edition 4)

🚫

🚀

🚫

GCI24

Returned SQL results should be limited

ESLint key : @ecocode/limit-db-query-results /// type : Back-end

🚧

🚀

✅

🚀

🚫

GCI25

Images should not have an empty source attribute

ESLint key : @ecocode/no-empty-image-src-attribute /// type : Front-end

❓

✅

❓

🚀

GCI26

Shorthand CSS notations should be used to reduce stylesheets size

ESLint key : @ecocode/prefer-shorthand-css-notations /// type : Front-end

❓

✅

❓

🚫

GCI27

Usage of system.arraycopy to copy arrays

Programs spend most of the time in loops. These can be resource consuming, especially when they integrate heavy processing (IO access). Moreover, the size of the data and processing inside the loops will not allow full use of hardware mechanisms such as the cache or compiler optimization mechanisms.

✅

🚫

GCI28

Optimize read file exceptions

✅

🚫

GCI29

CSS animations should be avoided

ESLint key : @ecocode/avoid-css-animations /// type : Front-end

❓

✅

❓

🚫

GCI30

Print stylesheet should be provided

ESLint key : @ecocode/provide-print-css /// type : Front-end

❓

✅

❓

🚫

GCI31

Lighter formats should be used for image files

ESLint key : … /// type : …

🚧

❓

✅

❓

🚀

GCI32

Initialize builder/buffer with the appropriate size

If you know in advance how many characters would be appended, initialize builder/buffer with the appropriate size. They will thus never have to be resized. This saves CPU cycles and therefore consumes less energy.

✅

🚫

GCI35

Using try…catch calls (on File Not Found error)

When an exception is thrown, a variable (the exception itself) is created in the catch block and destroyed at the end of the block. Creating this variable and destroying it consumes CPU cycles and RAM unnecessarily. That is why it is important not to use this construction and to prefer, as much as possible, a logical test. This new rule replace old GCI34 only for a particular use case (FileNotFoundException)

cnumr best practices (3rd edition) BP_047 (no longer exists in edition 4)

🚫

✅

🚀

✅

🚀

🚫

GCI36

Autoplay should be avoided for video and audio content

Autoplaying media consumes unnecessary energy, especially when users might not be actively engaging with the content.

cnumr best practices BP_4003

🚫

✅

🚫

🚧

GCI66

Use single quote (') instead of quotation mark (")

The shape using the quotation marks allows the developer to insert variables that will be substituted at run time. But if the string does not have a variable, use quotes instead. Thus, language will not look for variables to subtituture, which will reduce the consumption of CPU cycles.

cnumr best practices (3rd edition) BP_066 (no longer exists in edition 4)

🚀

✅

🚀

🚫

🚀

🚫

GCI67

Use the $i++ variable during an iteration

The $i form has the disadvantage of generating a tem-porary variable during incrementation, which is not the case with the $i form.

cnumr best practices (3rd edition) BP_067 (no longer exists in edition 4)

✅

🚀

🚫

GCI69

Calling a loop invariant function in a loop condition

Avoid calling loop invariant functions in loop conditions.

cnumr best practices (3rd edition) BP_069 (no longer exists in edition 4)

✅

🚀

🚫

🚀

✅

🚫

GCI72

Perform an SQL query inside a loop

Servers are optimized to process multiple selections, insertions, or changes in a single query or transaction. consume CPU cycles, RAM, and bandwidth unnecessarily.

cnumr best practices (3rd edition) BP_072

✅

🚀

✅

🚀

✅

🚫

GCI74

Write SELECT * FROM

The database server must resolve the fields based on the schema. If you are familiar with the diagram, it is strongly recommended to name the fields.

cnumr best practices (3rd edition) BP_074 (no longer exists in edition 4)

✅

🚀

✅

🚀

🚫

GCI75

Don’t concatenate strings in loops

Avoid repeated string allocations and consider using a StringBuilder instead.

🚫

❓

✅

🚫

GCI76

Usage of static collections

Avoid usage of static collections. If you want to use static collections make them final and create for example a singleton if needed containing the collections. The static fields are more complicated for the Garbage Collector to manage and can lead to memory leaks.

✅

🚫

GCI77

Usage Pattern.compile() in a non-static context

Avoid using Pattern.compile() in a non-static context. This operation requires a non negligible amount of computational power, Using a single match saves CPU cycles and RAM consumption.

✅

🚫

GCI78

Const parameter in batch update

Don’t set const parameter in batch update ⇒ Put its in query. Creating this parameter and destroying it consumes CPU cycles and RAM unnecessarily.

✅

🚫

GCI79

Free resources

try-with-resources Statement needs to be implemented for any object that implements the AutoCloseable interface, it save computer resources.

✅

🚫

GCI81

Specify struct layouts

When possible, specify struct layouts to optimize their memory footprint

🚫

✅

🚫

GCI82

Make variable constant

A variable is never reassigned and can be made constant

✅

🚀

✅

🚫

GCI83

Replace Enum ToString() with nameof

When no string format is applied, use nameof instead of ToString() for performance

🚫

✅

🚫

GCI84

Avoid async void methods

Use async Task methods instead, for performance, stability and testability

🚫

✅

🚫

GCI85

Make type sealed

Seal types that don’t need inheritance for performance reasons

🚫

✅

🚫

GCI86

GC.Collect should not be called

In most cases, the cost of calling GC.Collect far outweighs the benefits

🚫

✅

🚫

GCI87

Use collection indexer

Collection indexers should be used instead of Linq, when available

🚫

✅

🚫

GCI88

Dispose resource asynchronously

Resources that implement IAsyncDisposable should be disposed asynchronously

🚫

✅

🚫

GCI89

Avoid using function cache without limit

If a function has decorators without max size cache, the program will store unlimited data

❓

✅

❓

GCI90

Use Cast instead of Select to cast

Cast is optimized for this scenario and should be used

❓

✅

❓

GCI91

Use Where before OrderBy

Filter elements before sorting them for improved efficiency

❓

✅

❓

GCI92

Use string.Length instead of comparison with empty string

Comparing a string to an empty string is unnecessary and can be replaced by a call to string.Length which is more performant and more readable.

🚫

✅

🚫

GCI93

Return Task directly

Consider returning a Task directly instead of a single await

❓

✅

❓

GCI94

Use orElseGet instead of orElse

Parameter of orElse() is evaluated, even when having a non-empty Optional. Supplier method of orElseGet passed as an argument is only executed when an Optional value isn’t present. Therefore, using orElseGet() will save computing time.

Optimized use of Java Optional Else

✅

🚫

GCI203

Detect unoptimized file formats

When it is possible, to use svg format image over other image format

🚧

🚀

✅

🚀

🚫

GCI404

Avoid list comprehension in iterations

Use generator comprehension instead of list comprehension in for loop declaration

🚫

✅

🚫

GCI522

Sobriety: Brightness Override

To avoid draining the battery, iOS and Android devices adapt the brightness of the screen depending on the environment light.

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GCI523

Sobriety: Thrifty Geolocation (minTime)

High-precision geolocation typically requires more power from the device’s GPS hardware.

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GCI530

Sobriety: Torch Free

Turning on the torch mode programmatically must absolutely be avoided because the flashlight is one of the most energy-intensive component.

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Use official social media sharing buttons

These JavaScript plugins are very resource-intensive: to work, they require a large number of requests and download heavy files. It is better to prefer direct links.

cnumr best practices (3rd edition) BP_019

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Non-grouped similar CSS declarations

When multiple Document Object Model (DOM) elements have common CSS properties, declare them together in the same style sheet. This method reduces the weight of CSS.

cnumr best practices (3rd edition) BP_025

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Non-standard fonts used

Prefer standard fonts, as they are already present on the user’s computer, so they do not need to download them. This saves bandwidth, while speeding up the display of the site.

cnumr best practices (3rd edition) BP_029

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Non-outsourced CSS and Javascript

If you include CSS or JavaScript code in the body of the HTML file, while the HTML file is used by several pages (or even the entire site), this code must be transferred for each page requested by the user, which increases the volume of data transmitted.

cnumr best practices (3rd edition) BP_032

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Resize images browser-side

Do not resize images using the HEIGHT and WIDTH attributes of the HTML code. This approach requires transferring these images to their original size, wasting bandwidth and CPU cycles.

cnumr best practices (3rd edition) BP_034

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Modify the DOM when traversing it

Modifying the DOM (Document Object Model) as you traverse it can lead to situations where the loop becomes very resource-intensive, especially CPU cycles.

cnumr best practices (3rd edition) BP_041

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Edit DOM elements to make it invisible

When an element of the Document Object Model (DOM) needs to be modified by several properties, each change in style or content will generate a repaint or reflow.

cnumr best practices (3rd edition) BP_042

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Rules to be reworked / measured / clarified

This table lists rules proposed by the community but they have to be reworked / measured / clarified before being implemented in creedengo plugins. (Issues and PR are closed, but they can be reopen once rework launched)

Rule key	Language	Name	Description	Invalidation
CRJVM204	Java	Detect unoptimized file formats	We have to clarify and rework this rule for Java before accepting the implementation	Github discussion - issue<br/>Github discussion - PR
GCI22	Java	The use of methods for basic operations	We have to measure this rule for Java before accepting the implementation	Github discussion - issue<br/>Github discussion - PR
GCI22	PHP	The use of methods for basic operations	We have to measure this rule for PHP before accepting the implementation	Github discussion - issue
GCI53	Java	Using arrays in foreach loops	No good arguments and not enough green measures.	Github discussion with sources
GRSP0007	PHP	Prefer using foreach	We have to clarify and measure this rule for PHP before accepting the implementation	Github discussion - PR
GRSP0008	PHP	Avoid using relative path	We have to clarify and measure this rule for PHP before accepting the implementation	Github discussion - PR
	Java	Avoid returning a JPA Entity in a RestController	We have to clarify and measure this rule for Java before accepting the implementation	Github discussion - issue<br/>Github discussion - PR

Rule key

Language

Name

Description

Invalidation

CRJVM204

Java

Detect unoptimized file formats

We have to clarify and rework this rule for Java before accepting the implementation

Github discussion - issue<br/>Github discussion - PR

GCI22

Java

The use of methods for basic operations

We have to measure this rule for Java before accepting the implementation

Github discussion - issue<br/>Github discussion - PR

GCI22

PHP

The use of methods for basic operations

We have to measure this rule for PHP before accepting the implementation

Github discussion - issue

GCI53

Java

Using arrays in foreach loops

No good arguments and not enough green measures.

Github discussion with sources

GRSP0007

PHP

Prefer using foreach

We have to clarify and measure this rule for PHP before accepting the implementation

Github discussion - PR

GRSP0008

PHP

Avoid using relative path

We have to clarify and measure this rule for PHP before accepting the implementation

Github discussion - PR

Java

Avoid returning a JPA Entity in a RestController

We have to clarify and measure this rule for Java before accepting the implementation

Github discussion - issue<br/>Github discussion - PR

Deprecated rules

This table lists rules proposed by the community but deprecated in creedengo plugins with the justification. These rules will be completely deleted in next releases and moved to bottom deleted rules array.

Rule key Language Name Description Invalidation

Rule key	Language	Name	Description	Invalidation
EC34	Java / PHP	Using try…catch…finally calls	Implementation is too simple (only detection of presence of "try" statement) AND replaced by `GCI35` rule	Github discussion with measures : general/java / php

EC34

Java / PHP

Using try…catch…finally calls

Implementation is too simple (only detection of presence of "try" statement) AND replaced by GCI35 rule

Github discussion with measures : general/java / php

Refused / Deleted rules

This table lists rules proposed by the community but refused or/and deleted in creedengo plugins with the justification.

Rule key Language Name Description Invalidation

Rule key	Language	Name	Description	Invalidation
CRDOM203	HTML	HTML page must contain a doctype tag	The difference in performance is negligible, this rule is more related to the user experience.	Github discussion with sources
CRPYT	Python	Use numpy array instead of standard list	The use of numpy library to perform array manipulation is more energy efficient than the use of the standard list functions.	Github discussion with measures
EC4	Java	Avoid using global variables	Global variables do not exist in Java.	Github discussion with sources
EC8	JavaScript	Avoid using high accuracy geolocation	The rule has been merged with the rule GCI523	Github discussion with sources
EC34	Python	Using try…catch…finally calls	Implementation is too simple (only detection of presence of "try" statement) AND replaced by `GCI35` rule	Github discussion with measures : general/java / python
EC63	Java	Unnecessarily assigning values to variables	There are already 3 native SonarQube rules for Java.	Github discussion with sources
EC66	Python	Use single quote (') instead of quotation mark (")	Finally, not applicable for Python	Github discussion with sources
EC69	Python	Calling a loop invariant function in a loop condition	Finally, not applicable for Python	Github discussion with sources
EC75	Java	Don’t concatenate strings in loops	Optimizations on Java concatenation Strings are useless since JDK8	Github discussion with sources