I am trying to retrieve the data of an image in Javascript using XMLHttpRequest
.
var xhr = new XMLHttpRequest();
xhr.open("GET", "http://www.celticfc.net/images/doc/celticcrest.png");
xhr.onreadystatechange = function() {
if (xhr.readyState === 4) {
var resp = xhr.responseText;
console.log(resp.charCodeAt(0) & 0xff);
}
};
xhr.send();
The first byte of this data should be 0x89
, however any high-value bytes return as 0xfffd
(0xfffd & 0xff
being 0xfd
).
Questions such as this one offer solutions using the overrideMimeType()
function, however this is not supported on the platform I am using (Qt/QML).
How can I download the data correctly?
Google I/O 2011: HTML5 Showcase for Web Developers: The Wow and the How
var xhr = new XMLHttpRequest();
xhr.open('GET', 'http://www.celticfc.net/images/doc/celticcrest.png', true);
xhr.responseType = 'arraybuffer';
xhr.onload = function(e) {
if (this.status == 200) {
var uInt8Array = new Uint8Array(this.response); // Note:not xhr.responseText
for (var i = 0, len = uInt8Array.length; i < len; ++i) {
uInt8Array[i] = this.response[i];
}
var byte3 = uInt8Array[4]; // byte at offset 4
}
}
xhr.send();
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