javascript - Picture height and width before uploading - Stack Overflow

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I am trying to validate the image uploaded by the user. So, after the user adds its image, before uploading it on the server, I tried validating the image dimensions with the javascript code below but it won't work.

function check_image_dimensions(){
var t=document.getElementById("main_file_1");
e=t.clientWidth;

n="";
o="We could not upload your image because \n \n";
if (e<300) {
(n+="The height of the image must be greater than 300px \n";
}
if(i<300){
n+="The height of the image must be greater than 300px \n";
}

I also tried:

e=t.width;
i=t.height;

But it still doesn't work. What am I doing wrong?

Thank you!

I am trying to validate the image uploaded by the user. So, after the user adds its image, before uploading it on the server, I tried validating the image dimensions with the javascript code below but it won't work.

function check_image_dimensions(){
var t=document.getElementById("main_file_1");
e=t.clientWidth;

n="";
o="We could not upload your image because \n \n";
if (e<300) {
(n+="The height of the image must be greater than 300px \n";
}
if(i<300){
n+="The height of the image must be greater than 300px \n";
}

I also tried:

e=t.width;
i=t.height;

But it still doesn't work. What am I doing wrong?

Thank you!

• javascript
• image
• validation
• upload
• dimensions

Share Improve this question Follow asked Nov 6, 2013 at 23:10 user2961763user2961763 6311 silver badge99 bronze badges 2

• 1 What is main_file_1, an img tag, or the file input tag? – varfoo Commented Nov 6, 2013 at 23:16
• It's the id I gave to the image. I have: <input type="file" id="main_file_1" name="main_file_1"> – user2961763 Commented Nov 6, 2013 at 23:23

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1 Answer 1

Sorted by: Reset to default 8

Something like:

1) Put the image in a hidden <img/> element

See this example: MDN - Using files from web applications

2) Check the size (bounding box) of the <img/> element

if(img.getBoundingClientRect().width<300) ...

3) Alert the user (or not)

Here is a working version: JSFiddle.

Browser Compatability: Firefox 3.6+, Chrome 7+, IE 10+, Opera 12+

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