Is there a good way to have a user upload a hex file, traverse it for a specific hex string, and the...

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Is there a good way to have a user upload a hex file, traverse it for a specific hex string, and then edit the next 2 bytes?

Post Body

IE: user uploads a hex file. I search for “0A 1B CC 04”, find it, then replace the next two bytes and output the new hex.

This is what I have but it is VERY slow

    <!DOCTYPE HTML>
    <html>
    <head>
        <title>Reading Binary Data with the File API and JavaScript</title>
    </head>
    <body>                            
        <input id="browseOpen" type="file"/>
        <textarea id="derp">
        </textarea>

        <input type="button" id="TestBtn" value="derp!"/>

        <script type="text/javascript">
            let fileData;
            document.getElementById('TestBtn').style.display = "none";

            var fileInput = document.getElementById("browseOpen");


            var fileInput = document.getElementById("browseOpen");
            fileInput.onchange = function () {            
                var fr = new FileReader();
                fr.onloadend = function () {
                    var result = this.result;
                    var hex = "";
                    for (var i = 0; i < this.result.length; i  ) {
                        var byteStr = result.charCodeAt(i).toString(16);
                        if (byteStr.length < 2) {
                            byteStr = "0"   byteStr;
                        }
                        hex  = " "   byteStr;
                    }
                    //alert(hex);
                    fileData = hex;
                    document.getElementById('TestBtn').style.display = "";
                };
                fr.readAsBinaryString(this.files[0]);
            };

            document.getElementById('TestBtn').addEventListener("click", test);

            function test(){
                //document.getElementById('derp').value = fileData.replace('34 00 00 00 ac db', 'shit');

            }
        </script>
    </body>
    </html>

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isatrap

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Posted: 3 years ago
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External URL: reddit.com/r/learnjavasc...