noParameterAssign

JavaScript (and super languages)

摘要

¥Summary

规则生效日期：v1.0.0

¥Rule available since: v1.0.0
诊断类别：lint/style/noParameterAssign

¥Diagnostic Category: lint/style/noParameterAssign
此规则没有修复方案。

¥This rule doesn’t have a fix.
此规则的默认严重级别为 warning。

¥The default severity of this rule is warning.
来源：

¥Sources:
- 与 no-param-reassign 相同
  
  ¥Same as no-param-reassign

如何配置

¥How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "style": {
5
        "noParameterAssign": "error"
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      }
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    }
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  }
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}

描述

¥Description

禁止重新分配 function 参数。

¥Disallow reassigning function parameters.

对 function 参数的赋值可能会产生误导和混淆，因为修改参数也会改变 arguments 对象。这通常是无意的，并且表明程序员犯了错误。

¥Assignment to function parameters can be misleading and confusing, as modifying parameters will also mutate the arguments object. It is often unintended and indicative of a programmer error.

示例

¥Examples

无效

¥Invalid

1
function f(param) {
2
    param = 13;
3
}

code-block.js:2:5 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Assigning a function parameter is confusing.
  
    1 │ function f(param) {
  > 2 │     param = 13;
      │     ^^^^^
    3 │ }
    4 │ 
  
  ℹ The parameter is declared here:
  
  > 1 │ function f(param) {
      │            ^^^^^
    2 │     param = 13;
    3 │ }
  
  ℹ Developers usually expect function parameters to be readonly. To align with this expectation, use a local variable instead.

1
function f(param) {
2
    param++;
3
}

code-block.js:2:5 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Assigning a function parameter is confusing.
  
    1 │ function f(param) {
  > 2 │     param++;
      │     ^^^^^
    3 │ }
    4 │ 
  
  ℹ The parameter is declared here:
  
  > 1 │ function f(param) {
      │            ^^^^^
    2 │     param++;
    3 │ }
  
  ℹ Developers usually expect function parameters to be readonly. To align with this expectation, use a local variable instead.

1
function f(param) {
2
    for (param of arr) {}
3
}

code-block.js:2:10 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Assigning a function parameter is confusing.
  
    1 │ function f(param) {
  > 2 │     for (param of arr) {}
      │          ^^^^^
    3 │ }
    4 │ 
  
  ℹ The parameter is declared here:
  
  > 1 │ function f(param) {
      │            ^^^^^
    2 │     for (param of arr) {}
    3 │ }
  
  ℹ Developers usually expect function parameters to be readonly. To align with this expectation, use a local variable instead.

1
class C {
2
    constructor(readonly prop: number) {
3
        prop++;
4
    }
5
}

code-block.ts:3:9 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Assigning a function parameter is confusing.
  
    1 │ class C {
    2 │     constructor(readonly prop: number) {
  > 3 │         prop++;
      │         ^^^^
    4 │     }
    5 │ }
  
  ℹ The parameter is declared here:
  
    1 │ class C {
  > 2 │     constructor(readonly prop: number) {
      │                          ^^^^
    3 │         prop++;
    4 │     }
  
  ℹ Developers usually expect function parameters to be readonly. To align with this expectation, use a local variable instead.

有效

¥Valid

1
function f(param) {
2
    let local = param;
3
}

选项

¥Options

propertyAssignment

可以使用 propertyAssignment 选项配置 noParameterAssign 规则，该选项决定是否允许或禁止对函数参数进行属性赋值。默认情况下，propertyAssignment 设置为 allow。

¥The noParameterAssign rule can be configured using the propertyAssignment option, which determines whether property assignments on function parameters are allowed or denied. By default, propertyAssignment is set to allow.

1
{
2
    "options": {
3
        "propertyAssignment": "allow"
4
    }
5
}

允许：允许对函数参数进行属性赋值。这是默认行为。

¥allow: Allows property assignments on function parameters. This is the default behavior.
- 示例：
  
  ¥Example:

1
{
2
  "linter": {
3
    "rules": {
4
      "style": {
5
        "noParameterAssign": {
6
          "options": {
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            "propertyAssignment": "allow"
8
          }
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        }
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      }
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    }
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  }
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}

1
function update(obj) {
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    obj.key = "value"; // No diagnostic
3
}

拒绝：禁止对函数参数进行属性赋值，从而强制执行更严格的不可变性。

¥deny: Disallows property assignments on function parameters, enforcing stricter immutability.
- 示例：
  
  ¥Example:

1
{
2
  "linter": {
3
    "rules": {
4
      "style": {
5
        "noParameterAssign": {
6
          "options": {
7
            "propertyAssignment": "deny"
8
          }
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        }
10
      }
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    }
12
  }
13
}

1
function update(obj) {
2
    obj.key = "value"; // Diagnostic: Assignment to a property of function parameter is not allowed.
3
}

code-block.js:2:5 lint/style/noParameterAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Assigning to a property of a function parameter is confusing.
  
    1 │ function update(obj) {
  > 2 │     obj.key = “value”; // Diagnostic: Assignment to a property of function parameter is not allowed.
      │     ^^^
    3 │ }
    4 │ 
  
  ℹ Function callers usually don’t expect the parameters they pass in to be modified. To avoid mutation, create a new instance and return it to the caller.

noParameterAssign

摘要

如何配置

描述

示例

无效

有效

选项

propertyAssignment

相关链接