javascript - 编辑字节并将其添加到二进制文件(uint8array)

Question

我想在我通过 ajax 加载的二进制文件中添加一个字符串和一些二进制文件，例如 0x00(以将其作为二进制文件获取)

到目前为止，这是我的代码:

var ajax = new XMLHttpRequest();
ajax.open("GET", "test.bin", true);
ajax.responseType = "arraybuffer";

ajax.onload = function () {
    var byteArray = new Uint8Array(ajax.response);
    // What can i do?
};

ajax.send();

Answer 1

好吧，我终于可以解决它了:

var str = 'Injected!!!';

var injAr = [0x21,0xFE,str.length]; 
for (var i = 0; i < str.length; i++) { injAr.push(str.charCodeAt(i));}
injAr.push(0x00,0x3B);

var ajax = new XMLHttpRequest();
ajax.open("GET", "test.gif", true);
ajax.responseType = "arraybuffer";

ajax.onload = function () {
    var bAr = new Uint8Array(ajax.response), len = bAr.length - 1;
    window.newBAr = new Uint8Array(len + injAr.length);
    for (var i = 0; i < len; i++) { newBAr[i] = bAr[i];}
    for (var i = 0; i < injAr.length; i++) { newBAr[len + i] = injAr[i];}
}
ajax.send();

嗯，这是为了正确地向 gif 添加注释 block ，但它也可以用于 jpg、png，例如修改或添加 exif 元数据