Gathering detailed insights and metrics for eslint-plugin-pinia-getters-no-array-mutations
Gathering detailed insights and metrics for eslint-plugin-pinia-getters-no-array-mutations
Installations
npm install eslint-plugin-pinia-getters-no-array-mutationsDeveloper Guide
BETA
Typescript
No
Module System
CommonJS
Node Version
20.11.0
NPM Version
10.2.4
Releases
Unable to fetch releases
Download Statistics
Total Downloads
0
Last Day
0
Last Week
0
Last Month
0
Last Year
0
Maintainers
1
Package Meta Information
Latest Version
1.2.0
Package Id
eslint-plugin-pinia-getters-no-array-mutations@1.2.0
Unpacked Size
67.17 kB
Size
19.34 kB
File Count
14
NPM Version
10.2.4
Node Version
20.11.0
Published on
Feb 15, 2024
Total Downloads
Cumulative downloads
Total Downloads
NaN
Last Day
0%
NaN
Compared to previous day
Last Week
0%
NaN
Compared to previous week
Last Month
0%
NaN
Compared to previous month
Last Year
0%
NaN
Compared to previous year
Weekly Downloads
Monthly Downloads
Yearly Downloads
Dev Dependencies
4
eslint-plugin-pinia-getters-no-array-mutations
This ESLint plugin introduces a rule for Pinia, the intuitive, type-safe, and flexible store pattern for Vue.js applications. By ensuring that getters in Pinia stores avoid in-place array mutations on the store's state, it prevents side effects, hard-to-track reactivity issues and unexpected infinite recursive behavior, ensuring a smoother development experience and less frustrating bug hunts. :)
Installation
If you haven't installed eslint in your project yet, follow its installation guide.
Then, install this plugin:
1npm install eslint-plugin-pinia-getters-no-array-mutations --save-dev
Usage
To include the rule in your ESLint checks, add it to your .eslintrc configuration like this:
1{ 2 "plugins": [ 3 // ... other plugins 4 "pinia-getters-no-array-mutations" 5 ], 6 "rules": { 7 // ... other rules 8 "pinia-getters-no-array-mutations/no-array-mutations-on-state": "error", 9 } 10}
Fix
The rule offers an automatic fix in the form of creating a clone of the original structure via structuredClone.
Be aware that this changes the semantics of your code, therefore it is disabled by default. If you are not sure what
structuredClone does or if it's the right approach for you, please read the section
Understanding the Fix.
You can enable the automatic fix in you .eslintrc configuration like this:
1"rules": { 2 // ... 3 "pinia-getters-no-array-mutations/no-array-mutations-on-state": ["error", { "enableFix": true }] 4 // ... 5}
Executing the fix will wrap the affected property in a structuredClone() call:
1// Before: 2sortedDifferently: (state) => state.someArray.sort(sortFn) 3 4// After: 5sortedDifferently: (state) => structuredClone(state.someArray).sort(sortFn)
About the rule: no-array-mutations-on-state
This rule checks for and reports any usage of array methods that mutate the store's state directly within Pinia getters.
Examples
Invalid Code Examples
The rule will flag any use of mutating array methods that are directly applied to this, state, or any nested
properties within a Pinia getter function. These can modify your state in place and lead to infinite recursive behavior.
Here are some examples that will be flagged by the rule:
1const store = { 2 getters: { 3 // Using .reverse() directly on this.someArray 4 reversedArray: (state) => this.someArray.reverse(), 5 6 // Mutating a nested array on this 7 sortedNestedArray: (state) => this.nested.someArray.sort(sortFn), 8 9 // Same idea for state 10 sortedStateArray: (state) => state.someArray.sort(sortFn), 11 12 // Mutating a nested array on state 13 sortedStateNestedArray: (state) => state.nested.someArray.sort(sortFn), 14 } 15};
Valid Code Examples
The following code examples use non-mutating patterns and will not be flagged by the rule:
1const store = { 2 getters: { 3 // Making a shallow copy of an array on this before sorting - may still be dangerous if you have nested arrays 4 sortedArray: (state) => [...this.someArray].sort(sortFn), 5 sortedNestedArray: (state) => [...this.nested.someArray].sort(sortFn), 6 7 // Same for state 8 sortedStateArray: (state) => [...state.someArray].sort(sortFn), 9 sortedStateNestedArray: (state) => [...state.nested.someArray].sort(sortFn), 10 11 // Using structuredClone to deeply clone an array on this before sorting 12 sortedDeepCloneArray: (state) => structuredClone(this.someArray).sort(sortFn), 13 sortedStateDeepCloneNestedArray: (state) => structuredClone(state.nested.someArray).sort(sortFn), 14 } 15};
What This Rule Checks
- Any instance where
this,stateor any member likestate.someArraythis.deeply.nested.propertyis followed by a call to a mutating array method. - Usage of
push,pop,shift,unshift,splice,sort,reverse,fill, andcopyWithinon arrays that are part of the store's reactive state.
Limitations / What This Rule Doesn't Check
Mutating other stores
The rule currently does not cover cases where other stores' getters or properties are mutated. For example:
1getters: { 2 sortedDifferently: () => { 3 const otherStore = useOtherStore(); 4 otherStore.someArray.sort(sortFn); // Not currently flagged by this rule, but still dangerous 5 } 6}
Since the rule does not flag the mutation of other properties, e.g. from other stores, you may still end up with methods that mutate arrays in place. This is a trade-off because the alternative would be to make the rule very broad, which could end up causing a lot of false positives, e.g. flagging operations on non-reactive arrays. If you have a good approach to improve this, please open a pull request or raise an issue :)
Complex reactivity inheritance
If you build complex getters, for example by using Maps, Sets, Object.values or similar to get a subset of your state, and then use
methods that mutate this subset, it might affect the underlying reactive state. This rule is not made for complex
use cases like that.
Your copy method
The rule does not check the contents of your array. If you create a shallow copy of a deeply nested array, you may still end up mutating properties of the original state if you mutate it. Example:
1getters: { 2 sortedDifferently: () => { 3 const otherStore = useOtherStore(); 4 otherStore.someArray.sort(sortFn); // Not currently flagged by this rule, but still dangerous 5 } 6}
To avoid this, use a deep cloning
method like structuredClone or any library of your choosing, popular choices being lodash's
_.cloneDeep or klona.
Understanding the Automatic Fix: structuredClone Deep Cloning
This plugin offers an automatic fix to prevent array mutations by cloning the target array before applying methods like
.sort(). The cloning is done using the structuredClone function, a recent addition to the JavaScript language that
creates a deep clone of a given object, preserving the structure and data of the original without any reference to it.
Implications of Using structuredClone:
- Deep Cloning: Unlike shallow copy techniques,
structuredClonewill recursively copy all properties, leading to a completely new array while maintaining nested data. This is useful for preventing side effects in reactive state management but be mindful of any performance implications. - Compatibility:
structuredCloneis supported in modern browsers and Node.js environments; however, if you are targeting older environments, a polyfill or alternative cloning method may be necessary. Check a compatibility table like caniuse for up-to-date support information. - Performance Considerations: Deep cloning an entire structure can be more resource-intensive than shallow cloning. While this shouldn't be an issue for small to medium-sized arrays, it's important to be cautious with large or complex state objects, as the operation could impact performance or memory usage.
- Semantic Changes: Keep in mind that wrapping array operations with structuredClone results in a semantic change to your getters. The returned arrays will now be independent copies, any changes to them won't be reflected in the original state, and vice versa.
Alternatives
- If your state's array only consists of primitives, you may prefer to use
spread syntax like this:
[...state.shallowArray].sort(sortFn). This creates a shallow copy of your array. - If structuredClone does not meet your requirements, feel free to use any other cloning method or library like lodash's
_.cloneDeep or klona.
Example:
1import { cloneDeep } from 'lodash'; 2 3// ... 4getters: { 5 sortedArray: (state) => cloneDeep(state).sort(sortFn), // valid 6} 7// ...
Demo
The repo provides a demonstration of the rule.
- Clone the repo
- Navigate to the demo folder
- Install via
npm install - Lint via
npm run lint - You will see multiple errors reported by the rule
- More information can be found in
/demo/README.md.
Motivation
After one too many hard-to-track reactivity issues, maximum call stack size exceeded errors and infinite recursion
loops, I am no longer willing to spend time endlessly debugging code just to remember at some point that .sort
modifies arrays in place.
Contributing
Contributions are welcome! If you find any issues or have suggestions for improvements, please open an issue or submit a pull request.
License: ISC
© Fabian Mohr, 2024. All rights reserved.
No vulnerabilities found.
No security vulnerabilities found.