检查输入值是否不等于整数，然后不提交表单

Question

i have a simple php email form, but i am getting spam emails. I have added a check input, User have to fill the input. If input value equal to 12 then submit the form, otherwise don't submit the form with a popup error.(Please do the math.)

<form action="" method="post">
<input type="text" name="name" placeholder="name" required>
<input type="text" name="email" placeholder="email" required>
<input type="text" name="phone" placeholder="phone" required>

<div class="check">
   <label>6 x 2 =</label>
   <input type="text" name="not_robot" required="required">
</div>

<input type="submit" value="submit">
</form>

i am using php method below:

if(isset($_POST['not_robot']) !== 12 && isset($_POST['not_robot']) !== ''){
    echo '<script type="text/javascript">alert("Please do the math, if you are human.");</script>';
}else{
    //email script here
}

when i submit form, error popup appear saying "Please do the math, if you are human", but after i close the popup, it also send email. Any help appreaciated Thanks

PS: if check method is possible using javascript or jquery it would be a great help.

Answer 1

You need to test on the client:

Plain JS

window.onload=function() {
  document.querySelector("form").onsubmit=function(e) {
    var val = this.elements["not_robot"].value;
    return !isNaN(val) && parseInt(Number(val)) == val &&  !isNaN(parseInt(val, 10);
  }
}

jQuery:

$(function() {
  $("form").on("submit",function(e) {
    var val = $("[name='not_robot'"].val();
    if (isNaN(val) || !parseInt(Number(val)) == val ||  isNaN(parseInt(val, 10)) e.preventDefault();
  }
}

Answer 2

Don't try to prevent sending spam mail this way. My suggestion is to apply csrf protection and also google captcha. You can use this library for csrf protection. And for google captcha use this

Answer 3

Try to check when submitting the form. Go with below code or link-

JSFiddle

HTML Code-

<form action="" method="post">
  <input type="text" name="name" placeholder="name" required>
  <input type="text" name="email" placeholder="email" required>
  <input type="text" name="phone" placeholder="phone" required>

  <div class="check">
    <label>6 x 2 =</label>
    <input type="text" name="not_robot" required="required">
  </div>

  <input type="submit" value="submit">
</form>

JAVASCRIPT Code-

$('form').submit(function() {
      if (parseInt($('input[name="not_robot"]').val()) == 12) {
        return true;
      }
      else{
        alert('You not enterd the correct value');
        return false;
      }
    });

Answer 4

If you want to validate through PHP..Below is the way

if(is_numeric($_POST['not_robot']) && !empty($_POST['not_robot'])){
    echo '<script type="text/javascript">alert("Please do the math, if you are human.");</script>';
}else{
    //email script here
}

Answer 5

Ways :

• Use PHP exit() function to exits the current script execution.we can use this function with (or without) an message.

  Syntax : exit(message) OR exit()

• We can also use return;

  Here, the control will return to the script that invoked the running of that file.

Try this :

if(isset(($_POST['not_robot']) != '12') && (isset($_POST['not_robot']) !== '')){
    /* alert here */
    exit();
}else{
    //email script here
}

Answer 6

HTML:

<form action="" method="post" name="form1">
<input type="text" name="name" placeholder="name" required>
<input type="text" name="email" placeholder="email" required>
<input type="text" name="phone" placeholder="phone" required>

<div class="check">
   <label>6 x 2 =</label>
   <input type="text" name="not_robot" id="not_robot" required="required" />
</div>

<input type="button" value="submit" onClick="checkForm()">
</form>

JavaScipt:

function checkForm()
{

  if(document.getElementById('not_robot').value == "12" && document.getElementById('not_robot').value != "")
  {
    alert('ok');
    document.forms['form1'].submit();
  }else{
        alert('not ok');
      }

}