prefer-readonly
Require private members to be marked as
readonly
if they're never modified outside of the constructor.
此规则报告的一些问题可通过 --fix
ESLint 命令行选项自动修复。
该规则需要 类型信息 才能运行。
私有成员变量(无论是使用 private
修饰符还是私有 #
字段)都不允许在其声明类之外进行修改。
如果该类从不修改它们的值,则可以安全地将它们标记为 readonly
。
英:Private member variables (whether using the private
modifier or private #
fields) are never permitted to be modified outside of their declaring class.
If that class never modifies their value, they may safely be marked as readonly
.
如果私有成员从未在构造函数之外进行修改,则此规则报告的私有成员将被标记为 readonly
。
英:This rule reports on private members are marked as readonly
if they're never modified outside of the constructor.
module.exports = {
"rules": {
"@typescript-eslint/prefer-readonly": "error"
}
};
示例
- ❌ 不正确
- ✅ 正确
class Container {
// These member variables could be marked as readonly
private neverModifiedMember = true;
private onlyModifiedInConstructor: number;
#neverModifiedPrivateField = 3;
public constructor(
onlyModifiedInConstructor: number,
// Private parameter properties can also be marked as readonly
private neverModifiedParameter: string,
) {
this.onlyModifiedInConstructor = onlyModifiedInConstructor;
}
}
Open in Playgroundclass Container {
// Public members might be modified externally
public publicMember: boolean;
// Protected members might be modified by child classes
protected protectedMember: number;
// This is modified later on by the class
private modifiedLater = 'unchanged';
public mutate() {
this.modifiedLater = 'mutated';
}
// This is modified later on by the class
#modifiedLaterPrivateField = 'unchanged';
public mutatePrivateField() {
this.#modifiedLaterPrivateField = 'mutated';
}
}
Open in Playground选项
onlyInlineLambdas
你可以将 "onlyInlineLambdas": true
作为对象内的规则选项传递,以将检查限制为仅检查立即分配 lambda 值的成员。
英:You may pass "onlyInlineLambdas": true
as a rule option within an object to restrict checking only to members immediately assigned a lambda value.
{
"@typescript-eslint/prefer-readonly": ["error", { "onlyInlineLambdas": true }]
}
{ "onlyInlineLambdas": true }
选项的代码示例:
英:Example of code for the { "onlyInlineLambdas": true }
options:
- ❌ 不正确
- ✅ 正确
class Container {
private onClick = () => {
/* ... */
};
}
Open in Playgroundclass Container {
private neverModifiedPrivate = 'unchanged';
}
Open in Playground何时不使用它
如果你不尝试强制执行强大的不可变性保证,则此规则对于你的项目可能限制过多。
英:If you aren't trying to enforce strong immutability guarantees, this rule may be too restrictive for your project.
选项
该规则接受以下选项
type Options = [
{
onlyInlineLambdas?: boolean;
},
];
const defaultOptions: Options = [{ onlyInlineLambdas: false }];