Why cant parse JSON from file? - json

Question

We have empty JSON file
I want to write new JSON objects in this file, and get from it Array of JSON objects (and after simply append new JSONs to array by 'push')
I write to the file incoming JSON object:
fs.writeFileSync(tasks, updatedJsonStr, encoding='utf8');
where
updatedJsonStr = JSON.stringify({"isCompleted":false,"task":"dfgdfg","date":"25.06.2015"});
So in the file we see added object.
After we get from the file our JSON objects:
tasksJsonObj = JSON.parse(fs.readFileSync("tasks.json", "utf-8"));
Append new JSON object as string and write it again:
updatedJsonStr = JSON.stringify(tasksJsonObj) + ',' + JSON.stringify(newJsonTask);
fs.writeFileSync(tasks, updatedJsonStr, encoding='utf8');
So we see 2 JSON objects in the file.
!But when I try to read file with 2 JSON objects - I got an error when reading JSON from the file ([SyntaxError: Unexpected token ,]):
try{
tasksJsonObj = JSON.parse(fs.readFileSync(tasks, "utf-8"));
console.log('aaaaa' + JSON.stringify(tasksJsonObj));
return true;
}catch (err) {
console.log("its not ok!");
console.log(err);
return false;
}

Answer 1

Your JSON formation is wrong,
{"isCompleted":false,"task":"dfgdfg","date":"25.06.2015"}, {"newisCompleted":false,"task":"dfgdfg","date":"25.06.2015"}
this is what you will get after concat two JSON stringify, which is also invalid.
Your JSON should be like this
[ {"isCompleted":false,"task":"dfgdfg","date":"25.06.2015"}, {"newisCompleted":false,"task":"dfgdfg","date":"25.06.2015"} ]
for that you can do something like this
var tasks = [];
tasks.push( {"isCompleted":false,"task":"dfgdfg","date":"25.06.2015"}) );
so your update jsonstr would be
updatedJsonStr = JSON.stringify( tasks );
again if you want to append a new json string, you can do like this
tasksJsonObj = JSON.parse(fs.readFileSync("tasks.json", "utf-8"));
tasksJsonObj.push( newJsonTask );
and then stringify it and write it back to file.

Answer 2

If you are trying to "extend" the object:
https://lodash.com/docs#assign
deep extend (like jQuery's) for nodeJS
If you are trying to "push" new objects into an array, then you're almost there:
var updatedJsonStr = JSON.stringify([{"isCompleted":false,"task":"dfgdfg","date":"25.06.2015"}]);
fs.writeFileSync(tasks, updatedJsonStr, encoding='utf8');
var tasksJsonArr = JSON.parse(fs.readFileSync("tasks.json", "utf-8"));
tasksJsonArr.push(newJsonTask);

Answer 3

There's a little problem with what you are writing. If you want to have multiple JSONs next to each other, you should consider putting them into an array:
updatedJsonStr = [];
updatedJsonStr.push(JSON.stringify(tasksJsonObj));
updatedJsonStr.push(JSON.stringify(newJsonTask));
and then write them into file!