小编Jur*_*can的帖子

我想创建需要可选参数之一的函数类型。

据我所知，是制作条件类型，但问题是在函数打字稿中无法根据此条件缩小类型

type a = { propA: number };
type b = { propB: string };

type OneOfIsRequired = <T extends a | undefined, S extends b | undefined>
  (parameterOne: S extends undefined ? a : T, parameterTwo?: T extends undefined ? b : S, x: number) => any;

const fn: OneOfIsRequired = (a, b) => {
  if (a) {
    const propA = a.propA;
  } else {
    const propB = b.propB; // Object is possibly 'undefined'.. typescript can not narrow …

我有带输入的蚂蚁设计表单，我需要限制一些字符在输入中写入。

<Form.Item
              {...formItemLayout}
              label={this.props.intl.formatMessage({ id: 'customer.form.zipCode' })}
            >
              {getFieldDecorator('zip_code', {
                validateTrigger: 'onBlur',
                initialValue: this.props.addressFormDefaults ? this.props.addressFormDefaults.zip_code : '',
                rules: [
                  {
                    transform: (value) => typeof value === 'string' ? value.trim() : undefined,
                    required: true, message: this.props.intl.formatMessage({ id: 'validation.requiredField' }),
                  },
                ],
              })(
                <Input
                  type="number"
                  size="large"
                  className={this.props.useSmartForm ? `${this.props.smartFormClassInstance} ${SMARTFORM_CLASS.ZIP}` : undefined}
                  form={this.props.formId}
                  disabled={this.props.formDisabled}
                />,
              )}
            </Form.Item>

所以理想的解决方案是添加一些按键事件并验证它

<Input
  type="number"
  onKeyDown={(event) => {
    // some validation;
    if (someValidation()) {
      return true;
    }
    return false;
  }}
/>;

但从 ts 定义

onKeyPress?: KeyboardEventHandler<T>; …