File in JSON format

Question

And oh guys all beauty?

I’m having a rather silly question, but I couldn’t find an answer. I’ve been going through some websites and I saw that instead of them calling a request $.AJAX on the server to populate a dropdown for example, they call a link in format JSON.

For example:

meulocal.com.br/cidades.json 

How can I create this file? It is advantageous to use this way?

I appreciate the help.

Answer 1

You create a *.json file the way you create any text file. In a *.json can be declared any type of value that is accepted, such as null, object expression {}, expression of Array [], numerical values, String, Boolean and null, therefore, it cannot be vázio.

Differences:

• In an object you can only declare property names with quotes between them.
• if you want to escape characters, declare one to look like this: n (or \\, computably) in front of the character.

In Javascript, the object JSON includes two methods:

* `parse`: Interpreta uma string como JSON.
* `stringify`: Transforma um objeto em string, no formato de JSON.

Role model:

var data = JSON.parse('{"version": 0.5}');
alert("Version: " + data.version);

// Exemplo; expandindo o objeto retornado

with(JSON.parse('{"a": "bla\\nbla", "b": true, "c": "ey"}'))
    alert("a: " + a), // -> "bla\nbla"
    alert("b: " + b), // -> true
    alert("c: " + c); // -> "ey"

// Exemplo: inline

alert("a: " + JSON.parse('{"a": "inline"}').a) // -> "inline"

Remembering: Some old browsers may not support the object JSON. This is not worrying, but if you want to detect, make a condition like this: typeof window.JSON === "object", or use some "polyfill" existing.

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Advangioso? If you want a project to be easy to work with, JSON makes it easy to read and manipulate data. Disadvantage compared to comma separated data advantage (,), which decreases the amount of characters, is insignificant. I would say it is advantageous.

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The doubt in your comment is not related to JSON. You can index any string in an object and then index another object. This is normal in languages such as Lua, Javascript, etc:

var object = {index: {b: true}};
alert(object.index.a); // undefined
alert(object.index.b); // true
alert(object.b); // undefined