使用javascript单击提交后弹出空输入

Question

I want to display error when the user doesn't enter in the input field after he clicks on the submit button. This display should be displayed at right of the input field. But i can't seem to figure out how is that possible using php and javascript. Here is my code:

<?php include "head.php";?>
<div class="container">
<?php

    if(isset($_SESSION["error"]) && $_SESSION["error"] != ""){
            echo $_SESSION["error"];        
        }unset($_SESSION["error"]);
    if(isset($_SESSION["error1"]) && $_SESSION["error1"] != ""){
            echo $_SESSION["error1"];       
        }unset($_SESSION["error1"]);

    if(isset($_SESSION["warning"]) && $_SESSION["warning"] != ""){
            echo $_SESSION["warning"];      
        }unset($_SESSION["warning"]);
    if(isset($_SESSION["warning1"]) && $_SESSION["warning1"] != ""){
            echo $_SESSION["warning1"];     
        }unset($_SESSION["warning1"]);
    if(isset($_SESSION["success"]) && $_SESSION["success"] != ""){  
            echo $_SESSION["success"];      
        }unset($_SESSION["success"]);
?>
<form class="form-horizontal" action="loginprocess.php" method="post">

<!--username input--->
  <div class="form-group">
    <label for="inputEmail3" class="col-sm-3 control-label">username</label>
    <div class="col-sm-6">
      <input type="text" class="form-control" id="inputEmail3" placeholder="Email" name="username"> 
    </div>
  </div>
<!--password input --->
  <div class="form-group">
    <label for="inputPassword3" class="col-sm-3 control-
       label">Password</label>
    <div class="col-sm-6">
      <input type="password" class="form-control" id="inputPassword3" 
              placeholder="Password" name="password">
    </div>
  </div>
<!-- input file --->
<div class="form-group">
    <label for="exampleInputFile" class="col-sm-3 control-label">File 
            input</label>
    <div class="col-sm-6">    
    <input type="file" id="exampleInputFile" name="file">
    <!--<p class="help-block">Example block-level help text here.</p>-->
    </div>
  </div>

<!-- selecting country --->
<div class="form-group">
 <label for="country" class="col-sm-3 control-label">Select Country</label>
<div class="col-sm-6"> 
  <select class="form-control" id="country" name="country[]">
    Nepal
    <span class="caret"></span>
        <option><a href="#">Nepal</a></option>
        <option><a href="#">USA</a></option>
        <option><a href="#">Dubai</a></option>
    <option><a href="#">Nepal</a></option>
    <option><a href="#">USA</a></option>
        <option><a href="#">Dubai</a></option>
    <option><a href="#">Nepal</a></option>
        <option><a href="#">USA</a></option>
        <option><a href="#">Dubai</a></option>
 </select>
</div>
</div>
<!-- checkbox--->
  <div class="form-group">
    <div class="col-sm-offset-3 col-sm-6">
      <div class="checkbox">
        <label>
          <input type="checkbox" name="remember me"> Remember me
        </label>
      </div>
    </div>
  </div>
  <div class="form-group">
    <div class="col-sm-offset-3 col-sm-9">
      <button type="submit" class="btn btn-default">Sign in</button>
    </div>
  </div>
</form>
</div>
<script>
$(function () {
  $("[data-toggle="tooltip"]").tooltip()
})
</script>
<?php 
print_r ($_POST);
?>
<?php include "foot.php";?>

Answer 1

https://www.w3schools.com/js/js_validation.asp Check this. Alternatively you could work with php only and show the message after the form has been submitted (in form handler).

Here you have some more examples using bootstrap: http://1000hz.github.io/bootstrap-validator/

$(document).ready(function() {
  $('#contact_form').bootstrapValidator({
      // To use feedback icons, ensure that you use Bootstrap v3.1.0 or later
      feedbackIcons: {
        valid: 'glyphicon glyphicon-ok',
        invalid: 'glyphicon glyphicon-remove',
        validating: 'glyphicon glyphicon-refresh'
      },
      fields: {
        first_name: {
          validators: {
            stringLength: {
              min: 2,
            },
            notEmpty: {
              message: 'Please supply your first name'
            }
          }
        },
        last_name: {
          validators: {
            stringLength: {
              min: 2,
            },
            notEmpty: {
              message: 'Please supply your last name'
            }
          }
        },
        email: {
          validators: {
            notEmpty: {
              message: 'Please supply your email address'
            },
            emailAddress: {
              message: 'Please supply a valid email address'
            }
          }
        },
        phone: {
          validators: {
            notEmpty: {
              message: 'Please supply your phone number'
            },
            phone: {
              country: 'US',
              message: 'Please supply a vaild phone number with area code'
            }
          }
        },
        address: {
          validators: {
            stringLength: {
              min: 8,
            },
            notEmpty: {
              message: 'Please supply your street address'
            }
          }
        },
        city: {
          validators: {
            stringLength: {
              min: 4,
            },
            notEmpty: {
              message: 'Please supply your city'
            }
          }
        },
        state: {
          validators: {
            notEmpty: {
              message: 'Please select your state'
            }
          }
        },
        zip: {
          validators: {
            notEmpty: {
              message: 'Please supply your zip code'
            },
            zipCode: {
              country: 'US',
              message: 'Please supply a vaild zip code'
            }
          }
        },
        comment: {
          validators: {
            stringLength: {
              min: 10,
              max: 200,
              message: 'Please enter at least 10 characters and no more than 200'
            },
            notEmpty: {
              message: 'Please supply a description of your project'
            }
          }
        }
      }
    })
    .on('success.form.bv', function(e) {
      $('#success_message').slideDown({
        opacity: "show"
      }, "slow") // Do something ...
      $('#contact_form').data('bootstrapValidator').resetForm();

      // Prevent form submission
      e.preventDefault();

      // Get the form instance
      var $form = $(e.target);

      // Get the BootstrapValidator instance
      var bv = $form.data('bootstrapValidator');

      // Use Ajax to submit form data
      $.post($form.attr('action'), $form.serialize(), function(result) {
        console.log(result);
      }, 'json');
    });
});

#success_message {
  display: none;
}

<head>
  <script src="https://s.codepen.io/assets/libs/modernizr.js" type="text/javascript"></script>
</head>


<script src="//cdnjs.cloudflare.com/ajax/libs/bootstrap-validator/0.4.5/js/bootstrapvalidator.min.js"></script>
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<link href="//cdnjs.cloudflare.com/ajax/libs/jquery.bootstrapvalidator/0.5.0/css/bootstrapValidator.min.css" rel="stylesheet" />
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap-theme.min.css" rel="stylesheet" />
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css" rel="stylesheet" />
<div class="container">

  <form class="well form-horizontal" action=" " method="post" id="contact_form">
    <fieldset>

      <!-- Form Name -->
      <legend>Contact Us Today!</legend>

      <!-- Text input-->

      <div class="form-group">
        <label class="col-md-4 control-label">First Name</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>
            <input name="first_name" placeholder="First Name" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- Text input-->

      <div class="form-group">
        <label class="col-md-4 control-label">Last Name</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>
            <input name="last_name" placeholder="Last Name" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- Text input-->
      <div class="form-group">
        <label class="col-md-4 control-label">E-Mail</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-envelope"></i></span>
            <input name="email" placeholder="E-Mail Address" class="form-control" type="text">
          </div>
        </div>
      </div>


      <!-- Text input-->

      <div class="form-group">
        <label class="col-md-4 control-label">Phone #</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-earphone"></i></span>
            <input name="phone" placeholder="[phone]" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- Text input-->

      <div class="form-group">
        <label class="col-md-4 control-label">Address</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-home"></i></span>
            <input name="address" placeholder="Address" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- Text input-->

      <div class="form-group">
        <label class="col-md-4 control-label">City</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-home"></i></span>
            <input name="city" placeholder="city" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- Select Basic -->

      <div class="form-group">
        <label class="col-md-4 control-label">State</label>
        <div class="col-md-4 selectContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-list"></i></span>
            <select name="state" class="form-control selectpicker">
      <option value=" " >Please select your state</option>
      <option>Alabama</option>
      <option>Alaska</option>
      <option >Arizona</option>
      <option >Arkansas</option>
      <option >California</option>
      <option >Colorado</option>
      <option >Connecticut</option>
      <option >Delaware</option>
      <option >District of Columbia</option>
      <option> Florida</option>
      <option >Georgia</option>
      <option >Hawaii</option>
      <option >daho</option>
      <option >Illinois</option>
      <option >Indiana</option>
      <option >Iowa</option>
      <option> Kansas</option>
      <option >Kentucky</option>
      <option >Louisiana</option>
      <option>Maine</option>
      <option >Maryland</option>
      <option> Mass</option>
      <option >Michigan</option>
      <option >Minnesota</option>
      <option>Mississippi</option>
      <option>Missouri</option>
      <option>Montana</option>
      <option>Nebraska</option>
      <option>Nevada</option>
      <option>New Hampshire</option>
      <option>New Jersey</option>
      <option>New Mexico</option>
      <option>New York</option>
      <option>North Carolina</option>
      <option>North Dakota</option>
      <option>Ohio</option>
      <option>Oklahoma</option>
      <option>Oregon</option>
      <option>Pennsylvania</option>
      <option>Rhode Island</option>
      <option>South Carolina</option>
      <option>South Dakota</option>
      <option>Tennessee</option>
      <option>Texas</option>
      <option> Uttah</option>
      <option>Vermont</option>
      <option>Virginia</option>
      <option >Washington</option>
      <option >West Virginia</option>
      <option>Wisconsin</option>
      <option >Wyoming</option>
    </select>
          </div>
        </div>
      </div>

      <!-- Text input-->

      <div class="form-group">
        <label class="col-md-4 control-label">Zip Code</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-home"></i></span>
            <input name="zip" placeholder="Zip Code" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- Text input-->
      <div class="form-group">
        <label class="col-md-4 control-label">Website or domain name</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-globe"></i></span>
            <input name="website" placeholder="Website or domain name" class="form-control" type="text">
          </div>
        </div>
      </div>

      <!-- radio checks -->
      <div class="form-group">
        <label class="col-md-4 control-label">Do you have hosting?</label>
        <div class="col-md-4">
          <div class="radio">
            <label>
                                    <input type="radio" name="hosting" value="yes" /> Yes
                                </label>
          </div>
          <div class="radio">
            <label>
                                    <input type="radio" name="hosting" value="no" /> No
                                </label>
          </div>
        </div>
      </div>

      <!-- Text area -->

      <div class="form-group">
        <label class="col-md-4 control-label">Project Description</label>
        <div class="col-md-4 inputGroupContainer">
          <div class="input-group">
            <span class="input-group-addon"><i class="glyphicon glyphicon-pencil"></i></span>
            <textarea class="form-control" name="comment" placeholder="Project Description"></textarea>
          </div>
        </div>
      </div>

      <!-- Success message -->
      <div class="alert alert-success" role="alert" id="success_message">Success <i class="glyphicon glyphicon-thumbs-up"></i> Thanks for contacting us, we will get back to you shortly.</div>

      <!-- Button -->
      <div class="form-group">
        <label class="col-md-4 control-label"></label>
        <div class="col-md-4">
          <button type="submit" class="btn btn-warning">Send <span class="glyphicon glyphicon-send"></span></button>
        </div>
      </div>

    </fieldset>
  </form>
</div>
</div>
<!-- /.container -->

https://codepen.io/jaycbrf/pen/iBszr