无法在javascript中获取图像的高度和宽度

Question

I am trying to retreive the actual height and width of an image through javascript. The image source being used in my case is a BLOB which gets generated as soon as a user inserts a file.

Heres my code:

    var img = document.createElement('img');
    var blob = URL.createObjectURL(e.target.files[0]);
    img.src = blob;
    console.log(img);
    var w = img.width;
    var h = img.height;
    console.log("NEW IMAGE width", w);
    console.log("NEW IMAGE height: ", h);

Here are the logs:

<img src=​"blob:​http%3A/​/​localhost%3A3000/​af3e5a35-8c1c-40b5-ad5a-379c3ab1ec1d">​
NEW IMAGE width 0
NEW IMAGE height:  0

the blob is correct since I can view the image in my browser.

When I create another image in my console with the same blob and try to retreive the height and width everything works just fine.

But when I try to run it like that in my onChange event form the input i just get 0 for height and width.

Answer 1

you should get size after image loaded:

    img.onload = getSize;//measure after loading or you will get 0

Answer 2

Need to take the width and height after the image got loaded. So need to give some time to load the image.Else you will get zero size always.Take the width/height inside onload event.

var img = document.createElement('img');
    var blob = URL.createObjectURL(e.target.files[0]);
    img.src = blob;
    img.onload = function() {
      var w = img.width;
      var h = img.height;
      console.log("NEW IMAGE width", w);
      console.log("NEW IMAGE height: ", h);
    }

Answer 3

Try loading it first:

img.onload(function() {
    var w = img.width;
    var h = img.height;

    console.log("NEW IMAGE width", w);
    console.log("NEW IMAGE height: ", h);
});

Answer 4

How to get height and width of the image in blob objeact? example:

 $(function(){ $("input[name=file_name]").on('change',function(){ var url = window.URL || window.webkitURL || window.mozURL; var src = url.createObjectURL($(this)[0].files[0]); $("#box").html('<img src="'+src+'">'); $("#box img").attr('width','100'); $('img')[0].onload = function() { console.log($(this).height()); //get image height by jQuery console.log($(this)[0].height)// get image height by javascript console.log($(this)[0].naturalHeight);//get real height by javascript /** * if you want to get the image's width,you can use following code : * $(this).width(); * $(this)[0].width; * $(this)[0].naturalWidth; */ }; }) }) 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <form method="post" enctype="multipart/form-data"> <input type="file" name="file_name"> </form> <div id="box"></div>