语法错误：参数在字段中无效

¥Message

SyntaxError: 'arguments' is not allowed in class field initializer or static initialization block (V8-based)
SyntaxError: arguments is not valid in fields (Firefox)
SyntaxError: Unexpected identifier 'arguments'. Cannot reference 'arguments' in class field initializer. (Safari)

¥Error type

¥What went wrong?

类字段初始化表达式或类静态初始化块在其范围内没有 arguments。尝试访问它会导致语法错误。

¥A class field initializer expression or a class static initialization block does not have arguments in its scope. Trying to access it is a syntax error.

• 即使 arguments 绑定在父范围内（例如当类嵌套在非箭头函数中时），这也是正确的。
• 在此范围内声明的非箭头函数仍将绑定其自己的 arguments 并正常读取它。

¥Examples

function makeOne() {
  class C {
    args = { ...arguments }; // SyntaxError: arguments is not valid in fields
  }
  return new C();
}

let CArgs;
class C {
  static {
    CArgs = arguments; // SyntaxError: arguments is not valid in fields
  }
}

class C {
  args = {};
  constructor() {
    this.args = arguments; // You can use arguments in constructors
  }
  myMethod() {
    this.args = arguments; // You can also use it in methods
  }
}

function makeOne() {
  const _arguments = arguments;
  class C {
    args = { ..._arguments }; // Only the identifier is forbidden
  }
  return new C();
}

¥See also

• 类
• 公共类字段
• 静态初始化块