(Node.js) Convert a File's Character Encoding from UTF-8 to UFT-8-BOM

To add a utf-8 BOM to a file is just a matter of prepending these 3 bytes to the file: 0xEF 0xBB 0xBF.

This may be difficult in some programming languages, or it may be trivial in either. Therefore, the Chilkat solution you see here might be helpful, or in a language such as C++, the Chilkat solution isn't really necessary because it's easy to do yourself.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var charset = new chilkat.Charset();

    charset.FromCharset = "utf-8";
    charset.ToCharset = "bom-utf-8";

    var success = charset.ConvertFile("qa_data/txt/helloWorld.txt","qa_output/helloWorldBom.txt");
    if (success !== true) {
        console.log(charset.LastErrorText);
        return;
    }

    console.log("Success.");

}

chilkatExample();