pipe in a new line delimitated log file serialized using flatten -> get json serialized log file (circular refs discarded)

deflatten.js

#!/usr/bin/env node
const Flatted=function(n){"use strict";
/*! (c) 2020 Andrea Giammarchi */var t=JSON.parse,r=JSON.stringify,e=Object.keys,a=String,u="string",f={},i="object",c=function(n,t){return t},l=function(n){return n instanceof a?a(n):n},o=function(n,t){return typeof t===u?new a(t):t},s=function(n,t,r){var e=a(t.push(r)-1);return n.set(r,e),e};return n.parse=function(n,r){var u=t(n,o).map(l),s=u[0],p=r||c,v=typeof s===i&&s?function n(t,r,u,c){for(var l=[],o=e(u),s=o.length,p=0;p<s;p++){var v=o[p],y=u[v];if(y instanceof a){var g=t[y];typeof g!==i||r.has(g)?u[v]=c.call(u,v,g):(r.add(g),u[v]=f,l.push({k:v,a:[t,r,g,c]}))}else u[v]!==f&&(u[v]=c.call(u,v,y))}for(var h=l.length,d=0;d<h;d++){var w=l[d],O=w.k,S=w.a;u[O]=c.call(u,O,n.apply(null,S))}return u}(u,new Set,s,p):s;return p.call({"":v},"",v)},n.stringify=function(n,t,e){for(var a=t&&typeof t===i?function(n,r){return""===n||-1<t.indexOf(n)?r:void 0}:t||c,f=new Map,l=[],o=[],p=+s(f,l,a.call({"":n},"",n)),v=!p;p<l.length;)v=!0,o[p]=r(l[p++],y,e);return"["+o.join(",")+"]";function y(n,t){if(v)return v=!v,t;var r=a.call(this,n,t);switch(typeof r){case i:if(null===r)return r;case u:return f.get(r)||s(f,l,r)}return r}},n}({});
const { Transform } = require('stream');
const os = require('os');
const stringifyCircularSafe = (data) => {
  let cache = [];
  const str = JSON.stringify(data, function(key, value) {
      if (typeof value === 'object' && value !== null) {
          if (cache.indexOf(value) !== -1) {
              // Circular reference found, discard key
              return;
          }
          // Store value in our collection
          cache.push(value);
      }
      // preserving the pid key as an empty string will allow buyan cli to
      // recognize the log entry as a valid entry if no pid is available, eg. browser env
      if (typeof value === 'undefined' && key === 'pid') {
        return '';
      }
    return value;
  });
  cache = null; // Enable garbage collection
  return str;
} 
class ByLineTransform extends Transform {
  constructor(opts) {
    super(opts);
    this._brRe = /\r?\n/;
    this._buf = null;
    
  }
  _transform(chunk, encoding, cb) {
    let str;
    if (Buffer.isBuffer(chunk) || encoding === 'buffer') {
      str = chunk.toString('utf8');
    } else {
      str = chunk;
    }

    try {
      if (this._buf !== null) {
        this._buf += str;  
      } else {
        this._buf = str;  
      }
      const lines = this._buf.split(this._brRe);
      const lastIndex = lines.length - 1;
      for (let i = 0; i < lastIndex; i++) {
        this.push(lines[i]);
      }
      const lastLine = lines[lastIndex];
      if (lastLine.length) {
        this._buf = lastLine;
      } else {
        this._buf = null;
      }
      cb();
    } catch(err) {
      console.log('eror on stream')
      cb(err); // invalid data type;
    }
  }
  _flush(callback) {
    try {
      if(this._buf !== null) {
        this.push(this._buf);
        this._buf = null;
      }
    } catch (err) {
      callback(err);
    }
  }
};

return process.stdin.pipe(new ByLineTransform({
  decodeStrings: false, // Accept string input rather than Buffers
}))
.pipe(new Transform({
  construct(callback) {
    callback();
  },
  transform(chunk, encoding, cb) {
    const string = chunk.toString();
    try {
      this.push(stringifyCircularSafe(Flatted.parse(string))+os.EOL);
      cb();
    } catch(err) {
      cb(err); // invalid data type;
    }
  },
  flush(callback) {
  }
}))
.pipe(process.stdout);

package.json

{
  "name": "npx-script-template",
  "version": "0.0.0",
  "bin": "./deflatten.js"
}