Question

Server returns image only on POST request.

I should preload image.

How to put result to javascript object?

$.post('image.php', {params: complexParamsObject}, function(result) {
  var image = new Image();

  // put result to 'image' object
});

Answer 1

If you want a url return from post converted in an image tag then you can use this

var img = new Image(100,100); // width, height values are optional params 
img.src = result; //or may be result.url depending of what you got in return

if you want to return content of image you will have to return the content in base64 encoding. and using DataURLs you can create image element. this article shed some more light on it..

http://www.websiteoptimization.com/speed/tweak/inline-images/

EDIT:
a
yes base64 is a string representation.. Actually you will have to convert image in byte[] and then encode it to base64 string. and then return that string using post method…
where src=”data:image/gif;base64,(base64encoded image content here)

<img src="data:image/gif;base64,R0lGODlhEAAOALMAAOazToeHh0tLS/7LZv/0jvb29t/f3//Ub/
/ge8WSLf/rhf/3kdbW1mxsbP//mf///yH5BAAAAAAALAAAAAAQAA4AAARe8L1Ekyky67QZ1hLnjM5UUde0ECwLJoExKcpp
V0aCcGCmTIHEIUEqjgaORCMxIC6e0CcguWw6aFjsVMkkIr7g77ZKPJjPZqIyd7sJAgVGoEGv2xsBxqNgYPj/gAwXEQA7" 
width="16" height="14" alt="embedded folder icon">

also have a look at this thread for base64 encoding and image creation.
Convert and insert Base64 data to Canvas in Javascript