Submit a form with Javascript and handle it with ajaxForm

Question

I am currently changing my system in order to have a loading progress bar when I now submit my form.

In my old system, I had this form and this script to check if the file exists and is in the right format:

Index.php

<form  method="POST" enctype="multipart/form-data" id="myForm" action="upload.php">

    <input type="file" name="imageSent" id="imgFile" class="inputImg" />
    <label for="imgFile" class="labelForImgF">
        <span>Select Img</span>
    </label>

    <button type="button" class="btnSubmit" onclick='verifyImg();'>
        <span>Send</span>
    </button>

</form>

    <script>
function verifyImg() {
    document.getElementById("warning").innerHTML = "";
    var fileName = document.getElementById("imgFile");
    if(fileName.files.item(0) == null) {
        document.getElementById("warning").innerHTML = "You must select an img";
    } else {
        if(!isValidFileType(fileName.files.item(0).name,'image')) {
            document.getElementById("warning").innerHTML = "Bad format";
        } else {
            document.getElementById('myForm').submit();
            document.getElementById("warning").innerHTML = "Sucess";
        }
    }
}

var extensionLists = {}; 
extensionLists.image = ['jpg', 'nef', 'bmp', 'png', 'jpeg', 'svg', 'webp', '3fr', 'arw', 'crw', 'cr2', 'cr3', 'dng', 'kdc', 'mrw', 'nrw', 'orf', 'ptx', 'pef', 'raf', 'R3D', 'rw2', 'srw', 'x3f'];

function isValidFileType(fName, fType) {
return extensionLists[fType].indexOf(fName.toLowerCase().split('.').pop()) > -1;
}
</script>

And here is my new system, It works well with ajax but I can't check if the format is correct because as long as I put the onclick:verifyImg(); in my button the form submits without passing by the Ajax system.

Here is my new code:

<form  method="POST" enctype="multipart/form-data" id="myForm" action="upload.php">

    <input type="file" name="imageSent" id="imgFile" class="inputImg" />
    <label for="imgFile" class="labelForImgF">
        <span>Select Img</span>
    </label>

    <button class="btnSubmit">
        <span>Send</span>
    </button>

</form>
<div id="bararea">
    <div id="bar"></div>
</div>

<div id="percent"></div>
<div id="status"></div>
<script>
$(function() {
$(document).ready(function(){
    var bar = $('#bar')
    var percent = $('#percent');
    var status = $('#status');

    $('form').ajaxForm({
        beforeSend: function() {
            status.empty();
            var percentVal = '0%';
            bar.width(percentVal);
            percent.html(percentVal);
        },
        uploadProgress: function(event, position, total, percentComplete) {
            var percentVal = percentComplete + '%';
            percent.html(percentVal);
            bar.width(percentVal);
        },
        complete: function(xhr) {
            status.html(xhr.responseText);
        }
    });
});
});
</script>

These two systems work well separately, but I can't mix them, in order to validate my form with javascript and submit it with Ajax.

I think I'm not understanding well how Ajax works, can you help me?

I am a beginner please be indulgent.

Solution: I tried Chris G answer and changed the function beforeSend by beforeSubmit and now It works perfectly.

Code:

<form  method="POST" enctype="multipart/form-data" id="myForm" action="upload.php">

    <input type="file" name="imageSent" id="imgFile" class="inputImg" />
    <label for="imgFile" class="labelForImgF">
        <span>Select Img</span>
    </label>

    <button class="btnSubmit">
        <span>Send</span>
    </button>

</form>
<div id="bararea">
    <div id="bar"></div>
</div>

<div id="percent"></div>
<div id="status"></div>
    <script>
function verifyImg() {
    document.getElementById("warning").innerHTML = "";
    var fileName = document.getElementById("imgFile");
    if(fileName.files.item(0) == null) {
        document.getElementById("warning").innerHTML = "You must select an img";
        return false;
    } else {
        if(!isValidFileType(fileName.files.item(0).name,'image')) {
            document.getElementById("warning").innerHTML = "Bad format";
            return false;
        } else {
            return true;
            document.getElementById("warning").innerHTML = "Sucess";
        }
    }
}

var extensionLists = {}; 
extensionLists.image = ['jpg', 'nef', 'bmp', 'png', 'jpeg', 'svg', 'webp', '3fr', 'arw', 'crw', 'cr2', 'cr3', 'dng', 'kdc', 'mrw', 'nrw', 'orf', 'ptx', 'pef', 'raf', 'R3D', 'rw2', 'srw', 'x3f'];

function isValidFileType(fName, fType) {
return extensionLists[fType].indexOf(fName.toLowerCase().split('.').pop()) > -1;
}
</script>
<script>
$(document).ready(function(){
    var bar = $('#bar')
    var percent = $('#percent');
    var status = $('#status');

    $('form').ajaxForm({
        beforeSubmit: function() {
            if (!verifyImg()) return false ;
            status.empty();
            var percentVal = '0%';
            bar.width(percentVal);
            percent.html(percentVal);
        },
        uploadProgress: function(event, position, total, percentComplete) {
            var percentVal = percentComplete + '%';
            percent.html(percentVal);
            bar.width(percentVal);
        },
        complete: function(xhr) {
            status.html(xhr.responseText);
        }
    });
});
</script>

Have your verifyImg return true or false, based on whether the file checks out. Then do this in your beforeSend function: if (!verifyImg()) return false; This should stop the form submission dead in its tracks. Then change your code so clicking the submit button submits the form, so ajaxForm takes over. — user5734311
– user5734311, Commented Jan 26, 2019 at 15:04
You are wrapping in two loads: $(function() { $(document).ready(function(){ only $(function() { is needed — mplungjan
– mplungjan, Commented Jan 26, 2019 at 15:05
@ChrisG I tried your code but It doesn't seem to work, I updated my post, do you see something wrong ? — Melvin Auvray
– Melvin Auvray, Commented Jan 26, 2019 at 15:25
Maybe beforeSend was changed to beforeSubmit check on doc. malsup.com/jquery/form/#options-object — 서강원
– 서강원, Commented Jan 26, 2019 at 15:25

Willis · Accepted Answer · 2019-01-26 16:13:21Z

use this code, I've check it, it runs well. If you want to test the upload progress, In google browser's console, select network→then select slow 3G here:

otherwise, you can't see the upload progress increase, you will see 100% in a flash unless you photo has a extremely big size.

user can't select non image file by adding accept attribute to the input box accept="image/*", even if not using this attribute, the javascript will validate the file format by there code, you can add other types here if you need "(jpeg|png|bmp)":

    var file = $('input[name="photo"]').get(0).files[0];
    var matchArr = file.type.match(/image\/(jpeg|png|bmp)/);
    if (!matchArr) {
      alert("file type not allow!");
      return false;
    }

This is the full code：

$(document).ready(function() {
  $('input[type="button"]').on('click', function() {
    var file = $('input[name="photo"]').get(0).files[0];
    var matchArr = file.type.match(/image\/(jpeg|png|bmp)/);
    if (!matchArr) {
      alert("file type not allow!");
      return false;
    }

    var words = $('input[name="words"]').val();
    var formData = new FormData();
    formData.append('photo', file);
    formData.append('words', words);

    $.ajax({
      type: 'post',
      url: '',
      data: formData,
      //contentType must be false（otherwise it will use default value：application/x-www-form-urlencoded; charset=UTF-8, which is wrong）
      contentType: false,
      //tell jquery don't process data（otherwise it will throw an error：Uncaught TypeError: Illegal invocation）
      processData: false,
      xhr: function() {
        let xhr = new XMLHttpRequest();
        //listening upload progress
        xhr.upload.addEventListener('progress', function(e) {
          if (e.lengthComputable) {
            let progress = e.loaded / e.total;
            progress = Math.round(progress * 10000) / 100 + '%';
            $('.upload-progress').html(progress);
          }
        }, false);
        return xhr;
      },
      success: function(response) {
        console.log(response);
      }
    });
    return false;
  });
});

<html>

<head>
  <title>AjaxFormDataUpload</title>
  <meta content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" name="viewport" />
  <script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
  <style>
    #upload-form {
      width: 50%;
      margin: 0 auto;
      border: 1px solid blue;
    }
    
    .field {
      padding: 10px;
    }
    
    .submit-btn {
      text-align: center;
      font-size: 20px;
    }
  </style>
</head>

<body>
  <form id="upload-form">
    <div class="field">
      <input type="file" name="photo" accept="image/*">
      <span class="upload-progress"></span>
    </div>
    <div class="field">
      <input type="text" name="words">
    </div>
    <div class="submit-btn">
      <input type="button" value="submit">
    </div>
  </form>
</body>

</html>

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