How to append new JSON element to JSON_array?

Question

var taskArrObj = JSON.parse(fs.readFileSync("tasks.json"));
var newJsonObj = {xx:true, yy:"bbb", zz:"10."};

var updatedJsonObj = taskArrObj + newJsonObj ??? append JSON array with new JSON element?

res.json(updatedJsonObj);//send splitted JSON array in response

If taskArrObj is an array then use taskArrObj.push(newJSONObject) — Satpal
– Satpal, Commented Jun 24, 2015 at 13:01
whats the format of tasks.json? >> that's simply file: [{xx:true, yy:"bbb", zz:"10."} , {xx:true, yy:"bbb", zz:"10."}] — Spacemaster
– Spacemaster, Commented Jun 24, 2015 at 13:02

Hammad · Accepted Answer · 2015-06-24 13:01:26Z

1

use this:

var updatedJSON=taskArrObj.push(newJsonObj);

answered Jun 24, 2015 at 13:01

Hammad

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9 Comments

Hammad Over a year ago

It means your taskArrObj is empty, possibly task.json could not loaded into it

Spacemaster Over a year ago

Do you mean task.json file cannot be blank? So how data gonna consists empty task.json file?

Hammad Over a year ago

Yes you are trying to call push method on a object that does not exist. This is the error. Graham has given a explanation why task.json may not be loading

Spacemaster Over a year ago

So can I create empty JSON variable if my JSON file is empty?

Hammad Over a year ago

Thats just error checking. You can do that. If you specify encoding then file contents will be available in your variable

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CodingIntrigue · Accepted Answer · 2015-06-24 13:06:26Z

0

As per the docs:

If encoding is specified then this function returns a string. Otherwise it returns a buffer.

readFileSync returns a buffer if you don't specify an encoding. JSON.parse will only accept a String as a parameter. Pass an encoding in:

var taskArrObj = JSON.parse(fs.readFileSync("tasks.json", "utf8"));
taskArrObj.push(newJsonObj);

answered Jun 24, 2015 at 13:06

CodingIntrigue

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1 Comment

Spacemaster Over a year ago

How to convert my {xx:true, yy:"bbb", zz:"10."} to newJsonObj? for normally pushing into array ..

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