我可以将变量作为值分配给对象的键吗？

Question

这允许吗？

export class H{
passwordErrorMessage = 'Password must contain 1 small-case alphabet, 1 capital  alphabet, 1 digit, 1 special character. The length should be 6-10 characters.'
...

validatePassword(control: FormControl) {
...
    return (REG_EXP.test(password)) ? null : {
      validatePassword: { // check the class ShowErrorsComponent to see how validatePassword is used.
        valid: false,
        message:  this.passwordErrorMessage //can I do this?
      } 
    };
  }
}

对于我的一个测试用例，我收到以下错误

TypeError: Cannot read property 'passwordErrorMessage' of undefined
Error object: Property name: ngDebugContext, value: [object Object]
Error object: Property name: ngErrorLogger, value: function () { [native code] }
TypeError: Cannot read property 'passwordErrorMessage' of undefined
    at HelperService.validatePassword (webpack:///./src/app/helper.service.ts?:224:31)

好像this是undefined。我仍处于调试的早期阶段，但我的第一个疑问是 this 的用法是否正确？如果我将用法更改为 message: 'Password must contain 1 small-case alphabet, 1 capital alphabet, 1 digit, 1 special character. The length should be 6-10 characters.'

，一切正常

Answer 1

可以，但是您需要将 validatePassword 绑定到 class 或使用箭头函数将 this 上下文传递给函数。这应该有效：

export class H{
    passwordErrorMessage = 'Password must contain 1 small-case alphabet, 1 capital  alphabet, 1 digit, 1 special character. The length should be 6-10 characters.'
    ...

    validatePassword = (control: FormControl) => {
        ...
        return (REG_EXP.test(password)) ? null : {
          validatePassword: { // check the class ShowErrorsComponent to see how validatePassword is used.
            valid: false,
            message:  this.passwordErrorMessage
          } 
    };
  }
}

我可以将变量作为值分配给对象的键吗？

Can I assign a variable as value to an object's key?

javascript

angular6