setState每秒调用工作一次

Question

电子邮件部分也很好，当我提交表单时，它会更新。

更改passwordinvalid的函数是：

passwordValidator = (email) => {
    this.setState(() => {
      if (email === 'test') {
        this.setState({ passwordInvalid: true });
      }
      else {
        this.setState({ passwordInvalid: false });
      }
    })
  }

并且是这样称呼的：

  mySubmitHandler = (event) => {
    this.passwordValidator(this.state.email);
    if (this.state.passwordInvalid) {
      event.preventDefault();
      alert("Email: '" + this.state.email + "' is invalid.");
    }
    else {
      event.preventDefault();
      alert("Email address submitted: " + this.state.email);
    }
  }

例

Answer 1

正如你所指出的：

setState（）不会立即改变this.state，而是创建一个挂起的状态转换。

这意味着，您的set state调用将异步执行。

this.passwordValidator(this.state.email);
if (this.state.passwordInvalid) {

mySubmitHandler = (event) => {
  event.preventDefault();
  const isPasswordValid = this.passwordValidator(); // will get state value automatically then calculate if its valid
  this.setState({ passwordInvalid: isPasswordValid });
  if (isPasswordValid ) {
    alert("Email: '" + this.state.email + "' is invalid.");
  }
  else {
    alert("Email address submitted: " + this.state.email);
  }
}