How to preview an image before and after upload?

On input type=file add an event onchange="preview()"

For the function preview() type:

thumb.src=URL.createObjectURL(event.target.files[0]);

Live example:

function preview() {
   thumb.src=URL.createObjectURL(event.target.files[0]);
}
<form>
    <input type="file" onchange="preview()">
    <img id="thumb" src="" width="150px"/>
</form>

meVeekay's answer was good and am just making it more improvised by doing 2 things.

  1. Check whether browser supports HTML5 FileReader() or not.

  2. Allow only image file to be upload by checking its extension.

HTML :

<div id="wrapper">
    <input id="fileUpload" type="file" />
    <br />
    <div id="image-holder"></div>
</div> 

jQuery :

$("#fileUpload").on('change', function () {

    var imgPath = $(this)[0].value;
    var extn = imgPath.substring(imgPath.lastIndexOf('.') + 1).toLowerCase();

    if (extn == "gif" || extn == "png" || extn == "jpg" || extn == "jpeg") {
        if (typeof (FileReader) != "undefined") {

            var image_holder = $("#image-holder");
            image_holder.empty();

            var reader = new FileReader();
            reader.onload = function (e) {
                $("<img />", {
                    "src": e.target.result,
                        "class": "thumb-image"
                }).appendTo(image_holder);

            }
            image_holder.show();
            reader.readAsDataURL($(this)[0].files[0]);
        } else {
            alert("This browser does not support FileReader.");
        }
    } else {
        alert("Pls select only images");
    }
});

Try this: (For Preview)

<script type="text/javascript">
    function readURL(input) {
        if (input.files && input.files[0]) {
            var reader = new FileReader();

            reader.onload = function (e) {
                $('#blah').attr('src', e.target.result);
            }

            reader.readAsDataURL(input.files[0]);
        }
    }
</script>

<body>
    <form id="form1" runat="server">
        <input type="file" onchange="readURL(this);" />
        <img id="blah" src="#" alt="your image" />
    </form>
</body>

Working Demo here>


                    #######################
                    ###  the img page   ###
                    #######################


<script src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
<script src="https://malsup.github.com/jquery.form.js"></script>
<script type="text/javascript">
    $(document).ready(function(){
        $('#f').live('change' ,function(){
            $('#fo').ajaxForm({target: '#d'}).submit();
        });
    });
</script>
<form id="fo" name="fo" action="nextimg.php" enctype="multipart/form-data" method="post">
    <input type="file" name="f" id="f" value="start upload" />
    <input type="submit" name="sub" value="upload" />
</form>
<div id="d"></div>


                    #############################
                    ###    the nextimg page   ###
                    #############################


<?php
     $name=$_FILES['f']['name'];
     $tmp=$_FILES['f']['tmp_name'];
     $new=time().$name;
     $new="upload/".$new;
     move_uploaded_file($tmp,$new);
     if($_FILES['f']['error']==0)
     {
?>
     <h1>PREVIEW</h1><br /><img src="<?php echo $new;?>" width="100" height="100" />
<?php
     }
?>