Function has

sdk/src/CloudSocketClientLib.js:6928–7058

(name)

                                // Internal: Determines whether the native `JSON.stringify` and `parse`
                                // implementations are spec-compliant. Based on work by Ken Snyder.
                                function has(name) {
                                    if (has[name] !== undef) {
                                        // Return cached feature test result.
                                        return has[name];
                                    }
                                    var isSupported;
                                    if (name == "bug-string-char-index") {
                                        // IE <= 7 doesn't support accessing string characters using square
                                        // bracket notation. IE 8 only supports this for primitives.
                                        isSupported = "a" [0] != "a";
                                    } else if (name == "json") {
                                        // Indicates whether both `JSON.stringify` and `JSON.parse` are
                                        // supported.
                                        isSupported = has("json-stringify") && has("json-parse");
                                    } else {
                                        var value,
                                            serialized = '{"a":[1,true,false,null,"\\u0000\\b\\n\\f\\r\\t"]}';
                                        // Test `JSON.stringify`.
                                        if (name == "json-stringify") {
                                            var stringify = exports.stringify,
                                                stringifySupported = typeof stringify == "function" && isExtended;
                                            if (stringifySupported) {
                                                // A test function object with a custom `toJSON` method.
                                                (value = function() {
                                                    return 1;
                                                }).toJSON = value;
                                                try {
                                                    stringifySupported =
                                                    // Firefox 3.1b1 and b2 serialize string, number, and boolean
                                                    // primitives as object literals.
                                                    stringify(0) === "0" &&
                                                    // FF 3.1b1, b2, and JSON 2 serialize wrapped primitives as object
                                                    // literals.
                                                    stringify(new Number()) === "0" && stringify(new String()) == '""' &&
                                                    // FF 3.1b1, 2 throw an error if the value is `null`, `undefined`, or
                                                    // does not define a canonical JSON representation (this applies to
                                                    // objects with `toJSON` properties as well, *unless* they are nested
                                                    // within an object or array).
                                                    stringify(getClass) === undef &&
                                                    // IE 8 serializes `undefined` as `"undefined"`. Safari <= 5.1.7 and
                                                    // FF 3.1b3 pass this test.
                                                    stringify(undef) === undef &&
                                                    // Safari <= 5.1.7 and FF 3.1b3 throw `Error`s and `TypeError`s,
                                                    // respectively, if the value is omitted entirely.
                                                    stringify() === undef &&
                                                    // FF 3.1b1, 2 throw an error if the given value is not a number,
                                                    // string, array, object, Boolean, or `null` literal. This applies to
                                                    // objects with custom `toJSON` methods as well, unless they are nested
                                                    // inside object or array literals. YUI 3.0.0b1 ignores custom `toJSON`
                                                    // methods entirely.
                                                    stringify(value) === "1" && stringify([value]) == "[1]" &&
                                                    // Prototype <= 1.6.1 serializes `[undefined]` as `"[]"` instead of
                                                    // `"[null]"`.
                                                    stringify([undef]) == "[null]" &&
                                                    // YUI 3.0.0b1 fails to serialize `null` literals.
                                                    stringify(null) == "null" &&
                                                    // FF 3.1b1, 2 halts serialization if an array contains a function:
                                                    // `[1, true, getClass, 1]` serializes as "[1,true,],". FF 3.1b3