lib/atoms/json.js

1// Copyright 2012 WebDriver committers
2// Copyright 2012 Google Inc.
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8//      http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16/**
17 * @fileoverview Provides JSON utilities that uses native JSON parsing where
18 * possible (a feature not currently offered by Closure).
19 */
20
21goog.provide('bot.json');
22
23goog.require('bot.userAgent');
24goog.require('goog.json');
25goog.require('goog.userAgent');
26
27
28/**
29 * @define {boolean} NATIVE_JSON indicates whether the code should rely on the
30 * native {@code JSON} functions, if available.
31 *
32 * <p>The JSON functions can be defined by external libraries like Prototype
33 * and setting this flag to false forces the use of Closure's goog.json
34 * implementation.
35 *
36 * <p>If your JavaScript can be loaded by a third_party site and you are wary
37 * about relying on the native functions, specify
38 * "--define bot.json.NATIVE_JSON=false" to the Closure compiler.
39 */
40bot.json.NATIVE_JSON = true;
41
42
43/**
44 * Whether the current browser supports the native JSON interface.
45 * @const
46 * @see http://caniuse.com/#search=JSON
47 * @private {boolean}
48 */
49bot.json.SUPPORTS_NATIVE_JSON_ =
50    // List WebKit and Opera first since every supported version of these
51    // browsers supports native JSON (and we can compile away large chunks of
52    // code for individual fragments by setting the appropriate compiler flags).
53    goog.userAgent.WEBKIT || goog.userAgent.OPERA ||
54        (goog.userAgent.GECKO && bot.userAgent.isEngineVersion(3.5)) ||
55        (goog.userAgent.IE && bot.userAgent.isEngineVersion(8));
56
57
58/**
59 * Converts a JSON object to its string representation.
60 * @param {*} jsonObj The input object.
61 * @param {?(function(string, *): *)=} opt_replacer A replacer function called
62 *     for each (key, value) pair that determines how the value should be
63 *     serialized. By default, this just returns the value and allows default
64 *     serialization to kick in.
65 * @return {string} A JSON string representation of the input object.
66 */
67bot.json.stringify = bot.json.NATIVE_JSON && bot.json.SUPPORTS_NATIVE_JSON_ ?
68    JSON.stringify : goog.json.serialize;
69
70
71/**
72 * Parses a JSON string and returns the result.
73 * @param {string} jsonStr The string to parse.
74 * @return {*} The JSON object.
75 * @throws {Error} If the input string is an invalid JSON string.
76 */
77bot.json.parse = bot.json.NATIVE_JSON && bot.json.SUPPORTS_NATIVE_JSON_ ?
78    JSON.parse : goog.json.parse;