Javascript 如何仅在条件为真时提交表格

我正在尝试用express+NodeJS实现身份验证系统。到目前为止还不错，但现在我看到，即使在刷新页面时，表单也会提交到服务器。我的代码是这样的：

客户端：

submit(e) {
    let data = this.state; /// object with user's informations
    e.preventDefault()
    validate.form(this.state.username, this.state.email, this.state.password, this.state.confirm) // this returns true if everything is fine or returns the error string!

}

render() {
    return (<div>
        <form action="/login" onSubmit = {this.submit} method="post">
            <p>Username:</p>
            <input type="text" onChange = {this.getData} name="username" value = {this.state.username} />
            <p>Email</p>
            <input type="text" onChange={this.getData} name = "email"  value = {this.state.email} />
            <p>Password</p>
            <input type="text" onChange={this.getData} name = "password"  value = {this.state.password} />
            <p>Confirm Password</p>
            <input type="text" onChange={this.getData} name = "confirm"  value = {this.state.confirm} />
            <br/> <br/>
            <input type="Submit" value='Submit'  /> ///this is not working!
        </form>
    </div>)
}

---

TL；DR我只希望在validate.form（用户名、电子邮件、密码、确认）返回true时提交表单。我使用bodyParser作为模块来解析json

假设form.validate（）是同步的，只有当form.validate（）返回错误字符串时，才应该调用preventDefault

submitForm(e) { // avoid to use 'submit' as method name

    let data = this.state; /// object with user's informations
    let formValid = validate.form(this.state.username, this.state.email, this.state.password, this.state.confirm);

    if(formValid !== true) {
      e.preventDefault()
    }

    // else, if formValid is true, the default behaviour will be executed.
}

---

不要给函数命名

submit

，也不要使用

this。以这样的形式提交

，使用合适的事件处理程序和

addEventListener

可能的副本，我现在不在家测试它，但这应该可以工作。同时我做了一些修改，我想我会在服务器端使用验证方法，泰

submitForm(e) { // avoid to use 'submit' as method name

    let data = this.state; /// object with user's informations
    let formValid = validate.form(this.state.username, this.state.email, this.state.password, this.state.confirm);

    if(formValid !== true) {
      e.preventDefault()
    }

    // else, if formValid is true, the default behaviour will be executed.
}