How to Receive stderr with execSync Return Value for node.js

#!/usr/bin/node
"use strict";
varchild_process=require("child_process");


console.log("#Retrieved by redirecting to standard output.Mix with standard output";
// The last thing I'm doing is running the true command to make sure it's successful.
varls_stdout_and_err =child_process.execSync("ls exist.txt not_exist.txt2>&1;true");
console.log({ls_stdout_and_err:ls_stdout_and_err.toString()});


console.log("\n#Retrieved by redirecting to standard output.Discard the original standard output.");
varls_stderr =child_process.execSync(
        "ls exist.txt not_exist.txt2>&1>/dev/null;true";
console.log({ls_stderr:ls_stderr.toString()});


console.log("\n#Replace standard output with errors");
varls_stderr =child_process.execSync(
        "ls exist.txt not_exist.txt3>&1>&22>&3;true";
console.log({ls_stderr:ls_stderr.toString()});


console.log("\n#Retrieve by catching errors";
try{
    // The last time I'm running the false command is to make sure it fails.
    child_process.execSync("ls exist.txt not_exist.txt; false");
}
catch(err){
    console.log({
        ls_stdout —err.stdout.toString(),
        ls_stderr —err.stderr.toString(),
    });
}

#Retrieved by redirecting to standard output.be mixed with standard output
{ ls_stdout_and_err: 'ls:cannot access\'not_exist.txt\': No such file or directory\nexist.txt\n'}

# Retrieved by redirecting to standard output.discard the original standard output
{ ls_stderr: 'ls:cannot access\'not_exist.txt\': No such file or directory\n'}

# Obtain standard output and error replacement
exist.txt
{ ls_stderr: 'ls:cannot access\'not_exist.txt\': No such file or directory\n'}

# Retrieving by Error Catch
ls:cannot access 'not_exist.txt'—No such file or directory
{ ls_stdout: 'exist.txt\n',
  ls_stderr: 'ls:cannot access\'not_exist.txt\': No such file or directory\n'}