This matrix lists all the rules identified as implementable within the standard ecoCode plugin.
Some are applicable for different technologies.
- ✅ Rule included in current version of ecoCode
- 🚧 Rule implementation in progress
- 🚀 Rule to implement
- 🚫 Non applicable rule
| Rule key | Name | Description | Reference/Validation | Java | Php | JS | Python | Rust |
|---|---|---|---|---|---|---|---|---|
| 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 | 🚫 | 🚫 | 🚧 | 🚫 | 🚫 | |
| CSS shorthand notations not used | Reduces the weight of the style sheet. | cnumr best practices (3rd edition) BP_026 | 🚫 | 🚫 | 🚫 | 🚫 | 🚫 | |
| CSS print not included | This style sheet reduces the number of pages printed. | cnumr best practices (3rd edition) BP_027 | 🚫 | 🚫 | 🚫 | 🚫 | 🚫 | |
| 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 | 🚫 | 🚫 | 🚧 | 🚫 | 🚫 | |
| EC10 | Use unoptimized vector images | Less heavy SVG images using less bandwidth | cnumr best practices (3rd edition) BP_036 | 🚧 | 🚀 | 🚀 | ✅ | 🚀 |
| Using too many CSS/javascript animations | JavaScript/CSS animations can be very expensive in terms of CPU cycles and memory consumption. | cnumr best practices (3rd edition) BP_039 | 🚫 | 🚫 | 🚧 | 🚫 | 🚫 | |
| 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 | 🚫 | 🚫 | 🚀 | 🚫 | 🚫 | |
| Modify several CSS properties all at once | To limit the number of repaints/reflows, it is recommended not to modify properties one by one. (linter key : @ecocode/no-multiple-style-changes) |
cnumr best practices (3rd edition) BP_045 | 🚫 | 🚫 | ✅ | 🚫 | 🚫 | |
| EC34 | Using try...catch...finally calls (To be deleted becuse of new one EC35) | 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. | cnumr best practices (3rd edition) BP_047 (no longer exists in edition 4) | 🚀 | ✅ | 🚀 | ✅ | 🚀 |
| EC35 | Using try...catch calls (on File Not Found Exception) | 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 EC34 only for a particular use case (FileNotFoundException) | cnumr best practices (3rd edition) BP_047 (no longer exists in edition 4) | 🚀 | ✅ | 🚀 | ✅ | 🚀 |
| EC22 | 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) | 🚀 | ✅ | 🚀 | 🚀 | 🚀 |
| ??? | Call a DOM element multiple times without caching (linter key : @ecocode/no-multiple-access-dom-element) |
Access to the Document Object Model (DOM) is costly in terms of CPU resources (CPU cycles). Also, when you use the same DOM element from JavaScript multiple times, store its reference in a variable so that you do not go through the DOM again for the same element. | cnumr best practices (3rd edition) BP_049 | 🚫 | 🚫 | ✅ | 🚫 | 🚫 |
| EC4 | 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) | ✅ | ✅ | 🚀 | ✅ | 🚀 |
| EC53 | Using arrays in foreach loops | foreach deduplicates items in a list before starting the enumeration. It is therefore generally more economical to use a simple for loop when you have a good command of the collection. | cnumr best practices (3rd edition) BP_053 (no longer exists in edition 4) | ✅ | 🚀 | 🚀 | 🚫 | 🚀 |
| EC7 | 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) | 🚀 | 🚀 | 🚀 | ✅ | 🚀 |
| EC63 | Unnecessarily assigning values to variables | Avoid declaring and using variables when it is not indis-thinkable. Indeed, each allocation corresponds to the RAM occupied. | cnumr best practices (3rd edition) BP_063 (no longer exists in edition 4) | ✅ | 🚀 | 🚀 | 🚀 | 🚀 |
| EC66 | 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) | 🚀 | ✅ | 🚀 | 🚫 see |
🚀 |
| EC67 | 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) | ✅ | ✅ | 🚀 | 🚫 | 🚫 |
| EC69 | Calling a function in the declaration of a for loop | Avoid calling the function each time the loop is iterated. | cnumr best practices (3rd edition) BP_069 (no longer exists in edition 4) | ✅ | ✅ | 🚀 | ✅ | 🚀 |
| EC72 | 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 | ✅ | ✅ | 🚀 | ✅ | 🚀 |
| EC74 | 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) | ✅ | ✅ | 🚀 | ✅ | 🚀 |
| EC1 | Calling a Spring repository inside a loop | The use of Spring repository in a loop induces unnecessary calculations by the CPU and therefore superfluous energy consumption. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC3 | 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. | ✅ | ✅ | 🚀 | 🚫 | 🚀 | |
| EC2 | Multiple if-else statement | 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. | ✅ | ✅ | 🚀 | 🚧 | 🚀 | |
| EC76 | 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. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC77 | 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. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC75 | Concatenate Strings in loop | Don't concatenate Strings in loop. User StringBuilder instead. Strings are immutable so each time you concatenate a String, a new String is created. This is a waste of memory and CPU. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC78 | 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. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC79 | Free resources | try-with-resources Statement needs to be implemented for any object that implements the AutoCloseable interface, it save computer resources. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC32 | 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. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC28 | Optimize read file exceptions | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | ||
| EC5 | 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. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC27 | 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. | ✅ | 🚫 | 🚫 | 🚫 | 🚫 | |
| EC404 | Avoid list comprehension in iterations | Use generator comprehension instead of list comprehension in for loop declaration | 🚫 | 🚫 | 🚫 | ✅ | 🚫 | |
| EC203 | Detect unoptimized file formats | When it is possible, to use svg format image over other image format | 🚀 | 🚀 | 🚀 | ✅ | 🚀 | |
| Avoid high accuracy geolocation | Avoid using high accuracy geolocation in web applications (linter key : @ecocode/avoid-high-accuracy-geolocation) |
🚫 | 🚫 | ✅ | 🚫 | 🚫 | ||
| No import all from library | Should not import all from library (linter key : @ecocode/no-import-all-from-library) |
🚫 | 🚫 | ✅ | 🚫 | 🚫 | ||
| Prefer collections with pagination | Prefer API collections with pagination (linter key : @ecocode/prefer-collections-with-pagination) |
🚫 | 🚫 | ✅ | 🚫 | 🚫 |
This table lists rules proposed by the community but refused in ecoCode plugins with the justification.
| Language | Name | Description | Invalidation |
|---|---|---|---|
| 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 |
| 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 |