unicorn/prefer-class-fields Style
What it does
Prefers class field declarations over this assignments in constructors for static values.
Why is this bad?
Class field declarations are more readable and less error-prone than assigning static values to this in the constructor. Using class fields keeps the constructor cleaner and makes the intent clearer.
Examples
Examples of incorrect code for this rule:
ts
class Foo {
constructor() {
this.bar = 1;
}
}
class MyError extends Error {
constructor(message: string) {
super(message);
this.name = "MyError";
}
}
class Foo {
foo = "foo";
constructor() {
this.foo = "bar";
}
}Examples of correct code for this rule:
js
class Foo {
bar = 1;
}
class MyError extends Error {
name = "MyError";
}
class Foo {
foo = "bar";
}How to use
To enable this rule using the config file or in the CLI, you can use:
json
{
"rules": {
"unicorn/prefer-class-fields": "error"
}
}ts
import { defineConfig } from "oxlint";
export default defineConfig({
rules: {
"unicorn/prefer-class-fields": "error",
},
});bash
oxlint --deny unicorn/prefer-class-fieldsVersion
This rule was added in v1.20.0.