A common use of JSON is to exchange data to/from a web server.
When receiving data from a web server, the data is always a string.
Parse the data with JSON.parse(), and the data becomes a JavaScript object.
Sending Data
If you have data stored in a JavaScript object, you can convert the object into JSON, and send it to a server:
Example
const myObj = {name: "John", age: 31, city: "New York"};
const myJSON = JSON.stringify(myObj);
window.location = "demo_json.php?x=" + myJSON;
Receiving Data
If you receive data in JSON format, you can easily convert it into a JavaScript object:
Example
const myJSON = '{"name":"John", "age":31, "city":"New York"}';
const myObj = JSON.parse(myJSON);
document.getElementById("demo").innerHTML = myObj.name;
JSON From a Server
You can request JSON from the server by using an AJAX request
As long as the response from the server is written in JSON format, you can parse the string into a JavaScript object.
Example
Use the XMLHttpRequest to get data from the server:
const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
const myObj = JSON.parse(this.responseText);
document.getElementById("demo").innerHTML = myObj.name;
};
xmlhttp.open("GET", "json_demo.txt");
xmlhttp.send();
Take a look at json_demo.txt
Array as JSON
When using the JSON.parse() on JSON derived from an array, the method will return a JavaScript array, instead of a JavaScript object.
Example
JSON returned from a server as an array:
const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
const myArr = JSON.parse(this.responseText);
document.getElementById("demo").innerHTML = myArr[0];
}
}
xmlhttp.open("GET", "json_demo_array.txt", true);
xmlhttp.send();
Take a look at json_demo_array.txt
