JSON Objects

JSON objects are surrounded by curly braces {}. JSON objects are written in key/value pairs. Keys must be strings, and values must be a valid JSON data type (string, number, object, array, boolean or null). Keys and values are separated by a colon. Each key/value pair is separated by a comma.

Accessing Object Values

You can access the object values by using dot (.) notation:

myObj = { "name":"John", "age":30, "car":null };
x = myObj.name;

You can also access the object values by using bracket ([]) notation:

myObj = { "name":"John", "age":30, "car":null };
x = myObj["name"];

Looping an Object

You can loop through object properties by using the for-in loop:

myObj = { "name":"John", "age":30, "car":null };
for (x in myObj) {
  document.getElementById("demo").innerHTML += x;
}

In a for-in loop, use the bracket notation to access the property values:

myObj = { "name":"John", "age":30, "car":null };
for (x in myObj) {
  document.getElementById("demo").innerHTML += myObj[x];
}

Nested JSON Objects

Values in a JSON object can be another JSON object.

myObj = {
  "name":"John",
  "age":30,
  "cars": {
    "car1":"Ford",
    "car2":"BMW",
    "car3":"Fiat"
  }
 }

You can access nested JSON objects by using the dot notation or bracket notation:

x = myObj.cars.car2;
// or:
x = myObj.cars["car2"];

Modify Values

You can use the dot notation to modify any value in a JSON object:

myObj.cars.car2 = "Mercedes";

You can also use the bracket notation to modify a value in a JSON object:

myObj.cars["car2"] = "Mercedes";

Delete Object Properties

Use the delete keyword to delete properties from a JSON object:

delete myObj.cars.car2;