OnSubmit 调用调用 3 个函数并检查 return_type 的函数，但未调用 1 个函数

Question

从用户获取值的表单，OnSubmit 调用函数 check_three_func()

<form method="post" action="register_action.php" id="register_form" name="register_form"

 onsubmit="return check_three_func()">

  <br>

  <div class="form-group">

    <label for="uname">Name:</label>

    <input type="text" class="form-control" id="uname" placeholder="Enter Name " name="uname">

  </div>

  <div class="form-group">

    <label for="uemail">Email id: </label>

    <input type="email" class="form-control" id="uemail" placeholder="Enter Email ID" name="uemail">

    <!-- onkeyup="javascript:validate(this.value)" -->

    <span id="alert" style="display:none"></span>

  </div>

  <div class="form-group">

    <label for="upassword">Enter Password:</label>

    <input type="password" class="form-control" id="upassword" placeholder="Set password" name="upassword">

  </div>

  <div class="form-group">

    <label for="ucpassword">Confirm Password:</label>

    <input type="password" class="form-control" id="ucpassword" placeholder="Enter password again" name="ucpassword" >

  </div>

  <!-- captcha div -->

  <div class="form-group">

    <img src="captcha.php" class="rounded" alt="Captcha"><br>

    <label for="captcha">Enter Captcha: </label>

    <input type="text" class="form-control" id="captcha"  name="captcha" maxlength="6">

     <!-- onkeyup="javascript:captcha_func(this.value)" -->

     <span id="captcha-result" style="display:none"></span>

  </div>

  <button type="submit" class="btn btn-success" id="submit-button" >Submit</button>

</form>

check_three_func() 在代码中调用下面提到的 3 个函数并返回 return_type，因此如果为 false 则无法提交表单

function check_three_func(){

    var check_email_func=check_email();

    var click_to_func=click_to();

    var check_func=check();

    if( check_email_func==true && click_to_func==true && check_func==true){

      return true;

      console.log("all true");

    }

    else{

      return false;

      console.log(" false");

    }

}

Answer 1

将异步参数值更新为 false。如果 async 参数值为 false，则 send() 方法在收到响应之前不会返回。xhttp.open("GET","emailvalidate.php?uemail="+email,false);试试下面的代码它会工作。function check_email(){&nbsp; var email = document.getElementById("uemail").value;&nbsp; if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari&nbsp; &nbsp; xhttp=new XMLHttpRequest();}&nbsp;else {// code for IE6, IE5&nbsp; &nbsp; xhttp=new ActiveXObject("Microsoft.XMLHTTP");&nbsp; }&nbsp; result = true; // create a variable result and by default make it true.&nbsp; xhttp.onreadystatechange=function(){&nbsp; &nbsp; if (xhttp.readyState == 4 && xhttp.status == 200) {&nbsp; &nbsp; &nbsp; document.getElementById("alert").style.display="inline";&nbsp; &nbsp; &nbsp; if(xhttp.responseText=="EMP"){&nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML="<br><span class='badge badge-pill badge-info'>fill out emai id</span>";&nbsp; &nbsp; &nbsp; &nbsp; console.log("Email id empty return false");&nbsp; &nbsp; &nbsp; &nbsp; result = false;&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; else if(xhttp.responseText=="OK"){&nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML="<br><span class='badge badge-pill badge-success' >welcome new user</span>";&nbsp; &nbsp; &nbsp; //document.getElementById("submit-button").disabled = false;&nbsp; &nbsp; &nbsp; console.log("New email id return true");&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; else if(xhttp.responseText=="NO"){&nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML="<br><span class='badge badge-pill badge-danger'>Email Already Exist</span>";&nbsp; &nbsp; &nbsp; //document.getElementById("submit-button").disabled = true;&nbsp; &nbsp; &nbsp; console.log("Email id already exsist return false");&nbsp; &nbsp; &nbsp; result = false;&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; else{&nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML=xhttp.responseText;&nbsp; &nbsp; &nbsp; &nbsp; //document.getElementById("submit-button").disabled = true;&nbsp; &nbsp; &nbsp; &nbsp; console.log("Error fetching email id");&nbsp; &nbsp; &nbsp; &nbsp; result = false;&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; };&nbsp; xhttp.open("GET","emailvalidate.php?uemail="+email,false);&nbsp; xhttp.send();&nbsp; return result;&nbsp; //at last return the result.}

Answer 2

这check_email是一个异步函数。这就是为什么你没有得到返回结果。你必须调用下面的函数。function在关键字之前添加 async并在check_email function.async function check_three_func() {&nbsp; &nbsp; var check_email_func = await check_email();&nbsp; &nbsp; var click_to_func = click_to();&nbsp; &nbsp; var check_func = check();&nbsp; &nbsp; if (check_email_func && click_to_func && check_func) {&nbsp; &nbsp; &nbsp; &nbsp; return true;&nbsp; &nbsp; &nbsp; &nbsp; console.log("all true");&nbsp; &nbsp; }&nbsp; &nbsp; else {&nbsp; &nbsp; &nbsp; &nbsp; return false;&nbsp; &nbsp; &nbsp; &nbsp; console.log(" false");&nbsp; &nbsp; }}将您的 ajax 代码包装在一个 Promise 中，并根据响应解决或拒绝，然后返回该 Promise。function check_email() {&nbsp; &nbsp; return new Promise((resolve, reject) => {&nbsp; &nbsp; &nbsp; &nbsp; var email = document.getElementById("uemail").value;&nbsp; &nbsp; &nbsp; &nbsp; if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; xhttp = new XMLHttpRequest();&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; else {// code for IE6, IE5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; xhttp = new ActiveXObject("Microsoft.XMLHTTP");&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; xhttp.onreadystatechange = function () {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (xhttp.readyState == 4 && xhttp.status == 200) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").style.display = "inline";&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (xhttp.responseText == "EMP") {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML = "<br><span class='badge badge-pill badge-info'>fill out emai id</span>";&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; console.log("Email id empty return false");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; reject(false);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; else if (xhttp.responseText == "OK") {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML = "<br><span class='badge badge-pill badge-success' >welcome new user</span>";&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //document.getElementById("submit-button").disabled = false;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; console.log("New email id return true");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; resolve(true);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; else if (xhttp.responseText == "NO") {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML = "<br><span class='badge badge-pill badge-danger'>Email Already Exist</span>";&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //document.getElementById("submit-button").disabled = true;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; console.log("Email id already exsist return false");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; reject(false);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; else {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; document.getElementById("alert").innerHTML = xhttp.responseText;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //document.getElementById("submit-button").disabled = true;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; console.log("Error fetching email id");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; reject(false);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; };&nbsp; &nbsp; &nbsp; &nbsp; xhttp.open("GET", "emailvalidate.php?uemail=" + email, true);&nbsp; &nbsp; &nbsp; &nbsp; xhttp.send();&nbsp; &nbsp; });}