typescript/prefer-readonly Style
What it does
Require class members that are never reassigned to be marked readonly.
Why is this bad?
Members that never change should be declared readonly to make class invariants explicit and prevent accidental mutation.
Examples
Examples of incorrect code for this rule:
ts
class Counter {
private value = 0;
getValue() {
return this.value;
}
}Examples of correct code for this rule:
ts
class Counter {
private readonly value = 0;
getValue() {
return this.value;
}
}Configuration
This rule accepts a configuration object with the following properties:
onlyInlineLambdas
type: boolean
default: false
Restrict checks to members immediately initialized with inline lambda values.
How to use
To enable this rule using the config file or in the CLI, you can use:
json
{
"options": {
"typeAware": true
},
"rules": {
"typescript/prefer-readonly": "error"
}
}ts
import { defineConfig } from "oxlint";
export default defineConfig({
options: { typeAware: true },
rules: {
"typescript/prefer-readonly": "error",
},
});bash
oxlint --type-aware --deny typescript/prefer-readonlyVersion
This rule was added in v0.0.8.