Here is the HTML for image upload. By default it will show image files only in the browsing window because we have put accept="image/*". But we can still change it from the dropdown and it will show all files. So the Javascript part validates whether or not the selected file is an actual image.
<div class="col-sm-8 img-upload-section">
<input name="image3" type="file" accept="image/*" id="menu_images"/>
<img id="menu_image" class="preview_img" />
<input type="submit" value="Submit" />
</div>
Here on the change event we first check the size of the image. And in the second if condition we check whether or not it is an image file.
this.files[0].type.indexOf("image") will be -1 if it is not an image file.
document.getElementById("menu_images").onchange = function () {
var reader = new FileReader();
if(this.files[0].size>528385){
alert("Image Size should not be greater than 500Kb");
$("#menu_image").attr("src","blank");
$("#menu_image").hide();
$('#menu_images').wrap('<form>').closest('form').get(0).reset();
$('#menu_images').unwrap();
return false;
}
if(this.files[0].type.indexOf("image")==-1){
alert("Invalid Type");
$("#menu_image").attr("src","blank");
$("#menu_image").hide();
$('#menu_images').wrap('<form>').closest('form').get(0).reset();
$('#menu_images').unwrap();
return false;
}
reader.onload = function (e) {
// get loaded data and render thumbnail.
document.getElementById("menu_image").src = e.target.result;
$("#menu_image").show();
};
// read the image file as a data URL.
reader.readAsDataURL(this.files[0]);
};