Check image width and height before upload with Javascript

Question

I have a JPS with a form in which a user can put an image    lt div class  photo  gt       lt div gt Photo  max 240x240 and 100 kb   lt  div gt       lt input type  file  name  photo  id  photoInput  onchange  checkPhoto this    gt   lt  div gt    I have written this js   function checkPhoto target        if target files 0  type indexOf  image      -1            document getElementById  photoLabel   innerHTML    File not supported           return false            if target files 0  size  gt  102400            document getElementById  photoLabel   innerHTML    Image too big  max 100kb            return false            document getElementById  photoLabel   innerHTML           return true      which works fine to check file type and size  Now I want to check image width and height but I cannot do it  I have tried with target files 0  width but I get undefined  With other ways I get 0  Any suggestions

User · Answer

Attach the function to the onchange method of the input type file  onchange  validateimg this        function validateimg ctrl             var fileUpload   ctrl          var regex   new RegExp    a-zA-Z0-9 s     -      jpg  png  gif              if  regex test fileUpload value toLowerCase                   if  typeof  fileUpload files      undefined                     var reader   new FileReader                    reader readAsDataURL fileUpload files 0                    reader onload   function  e                        var image   new Image                        image src   e target result                      image onload   function                              var height   this height                          var width   this width                          if  height  lt  1100    width  lt  750                                alert  At least you can upload a 1100 750 photo size                                 return false                           else                              alert  Uploaded image has valid Height and Width                                 return true                                                                                   else                   alert  This browser does not support HTML5                     return false                          else               alert  Please select a valid Image file                 return false

User · Answer

function uploadfile ctrl        var validate   validateimg ctrl        if  validate            if  window FormData     undefined                ShowLoading                var fileUpload     ctrl  get 0               var files   fileUpload files                var fileData   new FormData                  for  var i   0  i  lt  files length  i                      fileData append files i  name  files i                                fileData append  username    Wishes                   ajax                   url   UploadWishesFiles                   type   POST                   contentType  false                  processData  false                  data  fileData                  success  function result                        var id     ctrl  attr  id                                id replace  txt    hdn    val result                            imgPictureEn   attr  src       Data Wishes     result  show                         HideLoading                                       error  function err                        alert err statusText                       HideLoading                                                else               alert  FormData is not supported

User · Answer

I agree  Once it is uploaded to somewhere the user s browser can access then it is pretty easy to get the size  As you need to wait for the image to load you ll want to hook into the onload event for img   var width  height   var img   document createElement  img    img onload   function             naturalWidth   naturalHeight  aren t supported on  lt IE9  Fallback to normal width height        The natural size is the actual image size regardless of rendering         The  normal  width height are for the   rendered   size       width    img naturalWidth     img width      height   img naturalHeight    img height           Do something with the width and height       Setting the source makes it start downloading and eventually call  onload  img src    http   your website com userUploadedImage jpg

User · Answer

x000D   x000D      const ValidateImg    file    gt   x000D          let img   new Image   x000D          img src   window URL createObjectURL file  x000D          img onload        gt    x000D              if img width     100  amp  amp  img height    100   x000D                  alert  Correct size    x000D                  return true  x000D                x000D              alert  Incorrect size    x000D              return true  x000D            x000D        x000D   x000D   x000D

User · Answer

You can do the steps for previewing the image without showing it which is supported on all browsers  Following js code shows you how to check the width and height   var file   e target files 0   if      jpe g png gif   i test file name         var reader   new FileReader        reader addEventListener  quot load quot   function              var image   new Image            image src   this result as string          image addEventListener  load   function                  console log  height    this height   width    this width                                         false                    reader readAsDataURL file      Based on Mozilla docs   The readAsDataURL method is used to read the contents of the specified Blob or File  When the read operation is finished  the readyState becomes DONE  and the loadend is triggered  At that time  the result attribute contains the data as a data  URL representing the file s data as a base64 encoded string   And the browser compatibility is listed too

User · Answer

function validateimg ctrl             var fileUpload       txtPostImg   0             var regex   new RegExp    a-zA-Z0-9 s     -      jpg  png  gif              if  regex test fileUpload value toLowerCase                    if  typeof  fileUpload files      undefined                      var reader   new FileReader                     reader readAsDataURL fileUpload files 0                    reader onload   function  e                         var image   new Image                         image src   e target result                      image onload   function                               var height   this height                          var width   this width                          console log this                           if   height  gt   1024    height  lt   1100   amp  amp   width  gt   750    width  lt   800                                 alert  Height and Width must not exceed 1100 800                                 return false                                                    alert  Uploaded image has valid Height and Width                             return true                                                         else                   alert  This browser does not support HTML5                     return false                          else               alert  Please select a valid Image file                 return false

User · Answer

The file is just a file  you need to create an image like so  var  URL   window URL    window webkitURL     quot  file quot   change function  e        var file  img      if   file   this files 0              img   new Image            var objectUrl    URL createObjectURL file           img onload   function                  alert this width    quot   quot    this height                URL revokeObjectURL objectUrl                      img src   objectUrl             Demo  http   jsfiddle net 4N6D9 1  I take it you realize this is only supported in a few browsers  Mostly firefox and chrome  could be opera as well by now  P S  The URL createObjectURL   method has been removed from the MediaStream interface  This method has been deprecated in 2013 and superseded by assigning streams to HTMLMediaElement srcObject  The old method was removed because it is less safe  requiring a call to URL revokeOjbectURL   to end the stream  Other user agents have either deprecated  Firefox  or removed  Safari  this feature feature  For more information  please refer here

User · Answer

This is the easiest way to check the size   let img   new Image   img src   window URL createObjectURL event target files 0   img onload        gt       alert img width         img height       Check for specific size  Using 100 x 100 as example  let img   new Image   img src   window URL createObjectURL event target files 0   img onload        gt       if img width     100  amp  amp  img height     100           alert  Nice  image is the right size  It can be uploaded              upload logic here           else           alert  Sorry  this image doesn t look like the size we wanted  It s       img width  x   img height  but we require 100 x 100 size image

User · Answer

In my view the perfect answer you must required is var reader   new FileReader       Read the contents of Image File  reader readAsDataURL fileUpload files 0    reader onload   function  e         Initiate the JavaScript Image object    var image   new Image         Set the Base64 string return from FileReader as source    image src   e target result       Validate the File Height and Width    image onload   function          var height   this height      var width   this width      if  height  gt  100    width  gt  100          alert  quot Height and Width must not exceed 100px  quot          return false            alert  quot Uploaded image has valid Height and Width  quot        return true

[javascript] Check image width and height before upload with Javascript

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