I made it that way:

if I have:

var jsonArg1 = new Object();
    jsonArg1.name = 'calc this';
    jsonArg1.value = 3.1415;
var jsonArg2 = new Object();
    jsonArg2.name = 'calc this again';
    jsonArg2.value = 2.73;

var pluginArrayArg = new Array();
    pluginArrayArg.push(jsonArg1);
    pluginArrayArg.push(jsonArg2);

to convert pluginArrayArg (which is pure javascript array) into JSON array:

var jsonArray = JSON.parse(JSON.stringify(pluginArrayArg))

Wow, seems it got a lot easier nowadays... 3 ways you can do it:

json = { ...array };

json = Object.assign({}, array);

json = array.reduce((json, value, key) => { json[key] = value; return json; }, {});

One other way could be this:

        var json_arr = {};
        json_arr["name1"] = "value1";
        json_arr["name2"] = "value2";
        json_arr["name3"] = "value3";

        var json_string = JSON.stringify(json_arr);

I decided to use the json2 library and I got an error about “cyclic data structures”.

I got it solved by telling json2 how to convert my complex object. Not only it works now but also I have included only the fields I need. Here is how I did it:

OBJ.prototype.toJSON = function (key) {
       var returnObj = new Object();
       returnObj.devid = this.devid;
       returnObj.name = this.name;
       returnObj.speed = this.speed;
       returnObj.status = this.status;
       return returnObj;
   }

Or try defining the array as an object. (var cars = {};) Then there is no need to convert to json. This might not be practical in your example but worked well for me.

because my array was like below: and I used .push function to create it dynamically

my_array = ["234", "23423"];

The only way I converted my array into json is

json = Object.assign({}, my_array);

Answered in 2022

I think this is the best and cleanest answer.

Using JSON.stringify(), we convert the JavaScript array to Json string. And using JSON.parse(), we convert Json string to a Json object.

var JsonObject, jsArray;

// JS array
jsArray = ["one", "two", "three"];

// Convert (js array) to (json object)
JsonObject = JSON.parse(JSON.stringify(jsArray));

// type
console.log(typeof(JsonObject));

// JsonObject
console.log(JsonObject);

If you have only 1 object like the one you asked, the following will work.

var x = [{'a':'b'}];
var b= JSON.stringify(x);
var c = b.substring(1,b.length-1);
JSON.parse(c); 

Shortest

To generate valid json from array of integers use

let json = `[${cars}]`

for more general arrays use JSON.stringify(cars) (for object with circular references use this)

let cars = [1,2,3]; cars.push(4,5,6);

let json = `[${cars}]`;

console.log(json);
console.log(JSON.parse(json)); // json validation

You can convert an array to JSON using the Object.assign function. The main issue that I hit with that is that Javascript arrays have a zero based integer key, which in turn allows to access the data in the array.

let fruits = ['Apple', 'Banana']
document.write(fruits[0])

Returns:

Apple

When you convert the array to JSON, you get

{"0": "Apple", "1: "Banana"}

JSON objects on the contrary usually contain arbitrary keys, such as:

{ "some_key": "some value", "other_key: "some other value" }

Happily, you can create a list of items, which works pretty much as an array and then use Object.assign as if it was an array, then convert the output to a JSON object

var items = {};
items["some_key"]="some value";
items["other_key"]="some other value";
const jsonString = JSON.stringify(Object.assign({}, items)) 
const json_obj = JSON.parse(jsonString);

The advantage of working with item lists is that you don't have to deal with the JSON data as a string or quotes, commas etc... You can instead just manage the item object filling data in or removing it. When you are done you just convert the item variable to a JSON object and do whatever you need to do with it.

With your cars array: var cars = [2,3,..]. You can use for loop like this

    var carArray = new Array();  

    for(var c in cars) {
      var jsonObj = new Object();
      jsonObj.car_id = cars[c];
      carArray.push(jsonObj);
    }