How can I retrieve an image as a Blob using jQuery's ajax method?

Using jQuery's ajax Method to Retrieve Images as Blobs

Background:
As discussed in a previous question, there is a need to retrieve an image using jQuery and store it as a Blob for subsequent use in a POST request. However, jQuery's dataTypes do not explicitly mention images.

Problem:
The current code in CoffeeScript (and its JavaScript equivalent) attempts to retrieve an image using jQuery.get() and store it in a FormData object as a Blob. However, this approach results in corrupt images due to a mismatch in data types.

Question:
Is there a feasible method to retrieve an image as a Blob using jQuery's ajax method?

Answer:

Approach 1: Using Native XMLHttpRequest

It is not possible to retrieve an image as a Blob using jQuery's ajax method alone. However, utilizing native XMLHttpRequest provides a solution. Here's a JavaScript snippet:

var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function(){
    if (this.readyState == 4 && this.status == 200){
        //this.response is what you're looking for
        handler(this.response);
        console.log(this.response, typeof this.response);
        var img = document.getElementById('img');
        var url = window.URL || window.webkitURL;
        img.src = url.createObjectURL(this.response);
    }
}
xhr.open('GET', 'http://jsfiddle.net/img/logo.png');
xhr.responseType = 'blob';
xhr.send(); 

In this code, an XMLHttpRequest object is created, and its responseType is set to 'blob'. The onreadystatechange event is used to handle the response and create an object URL for the image.

Approach 2: Using jQuery 3

However, it is worth mentioning that with jQuery version 3, it is now possible to retrieve images as Blobs. Here's a revised JavaScript snippet using jQuery 3:

$.ajax({
    url:'https://images.unsplash.com/photo-1465101108990-e5eac17cf76d?ixlib=rb-0.3.5&q=85&fm=jpg&crop=entropy&cs=srgb&ixid=eyJhcHBfaWQiOjE0NTg5fQ%3D%3D&s=471ae675a6140db97fea32b55781479e',
    cache: false,
    xhr:function(){// Seems like the only way to get access to the xhr object
        var xhr = new XMLHttpRequest();
        xhr.responseType = 'blob'
        return xhr;
    },
    success: function(data){
        var img = document.getElementById('img');
        var url = window.URL || window.webkitURL;
        img.src = url.createObjectURL(data);
    },
    error:function(){
        
    }
});

In this snippet, we use jQuery's xhr() function to obtain access to the XMLHttpRequest object and set its responseType to 'blob'. This allows us to retrieve the image as a Blob and use it as desired.

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