index.js

Tail = require('tail').Tail;
var path = require("path")
var filename = path.resolve(process.argv[2]);
tail = new Tail(filename);

tail.on("line", function(data) {
  try{
    var parsed = JSON.parse(data)
    console.log(JSON.stringify(parsed, null, "  "))
  }catch(e){
    console.log(data);
  }
});

package.json

{
  "name": "hotail",
  "version": "0.0.0",
  "main": "index.js",
  "dependencies": {
    "tail": "^0.3.5"
  },
  "devDependencies": {},
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}