JavaScript JSON stringify() Method

Definition and Usage

The JSON.stringify() method converts a JavaScript object to a string.

When sending data to a Web server, the data must be a string.

Instance

Example 1

Stringify a JavaScript object:

var obj = { "name":"Bill", "age":19, "city":"Seattle"};
var myJSON = JSON.stringify(obj);
document.getElementById("demo").innerHTML = myJSON;

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Example 2

Use a replacement function:

/* Replace the "city" value with uppercase:*/
var obj = { "name":"Bill", "age":"19", "city":"Seattle"};
var text = JSON.stringify(obj, function (key, value) {
  if (key == "city") {
    return value.toUpperCase();
  } else {
    return value;
  }
});

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Example 3

Usage space Parameters:

/* Insert 10 space characters for each space:*/
var obj = { "name":"Bill", "age":"19", "city":"Seattle"};
var text = JSON.stringify(obj, null, 10);

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Example 4

Usage space Parameters:

/* Insert the word SPACE for each space:*/
var obj = { "name":"Bill", "age":"19", "city":"Seattle"};
var text = JSON.stringify(obj, null, "SPACE");

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Syntax

JSON.stringify(obj, replacer, space)

Parameter Value

Parameter Description
obj Required. The value to be converted to a string.
replacer

Optional. A function or array used to convert the result.

If the parameter is a function, during the serialization process, each property of the value to be serialized will be converted and processed by this function;

If the parameter is an array, only the property names included in this array will be serialized into the final JSON string;

If the parameter is null or not provided, all properties of the object will be serialized.
space

Optional. A string or numeric value. Specify the whitespace string used for indentation to beautify the output (pretty-print).

If the parameter is a number, it represents how many spaces; the maximum is 10. If this value is less than 1, it means there are no spaces;

If the parameter is a string (when the string length exceeds 10 letters, take the first 10 letters), the string will be used as spaces;

If the parameter is not provided (or is null), there will be no spaces.

Technical Details

Return Value: A String
JavaScript Version: ECMAScript 5

Browser Support

The numbers in the table indicate the first browser version that fully supports this method.

Methods Chrome IE Firefox Safari Opera
stringify() 4.0 8.0 3.5 4.0 11.5

Related Pages

JSON Tutorial:Introduction to JSON