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JSON Stringify

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A common use of JSON is to exchange data to/from a web server.

When sending data to a web server, the data has to be a string.

Convert a JavaScript object into a string with JSON.stringify().

Stringify a JavaScript Object #

Imagine we have this object in JavaScript:

var obj = { name: "John", age: 30, city: "New York" };

 

Use the JavaScript function JSON.stringify() to convert it into a string.

var myJSON = JSON.stringify(obj);

myJSON is now a string, and ready to be sent to a server:

Example #

var obj = { name: "John", age: 30, city: "New York" }; var myJSON = JSON.stringify(obj); document.getElementById("demo").innerHTML = myJSON;

You will learn how to send JSON to the server in the next chapter.

Stringify a JavaScript Array #

It is also possible to stringify JavaScript arrays:

Imagine we have this array in JavaScript:

var arr = [ "John", "Peter", "Sally", "Jane" ];

Use the JavaScript function JSON.stringify() to convert it into a string.

var myJSON = JSON.stringify(arr);

The result will be a string following the JSON notation.

 

myJSON is now a string, and ready to be sent to a server:

Example #

var arr = [ "John", "Peter", "Sally", "Jane" ]; var myJSON = JSON.stringify(arr); document.getElementById("demo").innerHTML = myJSON;

You will learn how to send JSON to the server in the next chapter.

Exceptions #

Stringify Dates #

In JSON, date objects are not allowed. The JSON.stringify() function will convert any dates into strings.

Example #

var obj = { name: "John", today: new Date(), city : "New York" }; var myJSON = JSON.stringify(obj); document.getElementById("demo").innerHTML = myJSON;

You can convert the string back into a date object at the receiver.

Stringify Functions #

In JSON, functions are not allowed as object values.

The JSON.stringify() function will remove any functions from a JavaScript object, both the key and the value:

Example #

var obj = { name: "John", age: function () {return 30;}, city: "New York"}; var myJSON = JSON.stringify(obj); document.getElementById("demo").innerHTML = myJSON;

This can be omitted if you convert your functions into strings before running the JSON.stringify() function.

Example #

var obj = { name: "John", age: function () {return 30;}, city: "New York" }; obj.age = obj.age.toString(); var myJSON = JSON.stringify(obj); document.getElementById("demo").innerHTML = myJSON;

If you send functions using JSON, the functions will lose their scope, and the receiver would have to use eval() to convert them back into functions.

Browser Support #

The JSON.stringify() function is included in JavaScript (ECMAScript) and is supported in all major browsers.

chrome internet explorer Mozila firefox Safari Opera
Yes 8.0 3.5 4.0 10.0

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