JSON-Expressible

An ES5 Javascript micro library that determines whether a value can be expressed as JSON.

• Checks whether the value is a valid JSON type (string, number, boolean, null, object, or array).

• Recursively checks whether object children and/or array elements are valid JSON types.

• Checks whether there are any circular references.

The motivation for this library is twofold:

1. The JSON.stringify() function does not throw an error when it encounters non-JSON values like undefined and NaN. Instead, it omits the values or converts them to null in the returned serialization. As a result, parsing the serialization does not return the original value.

2. It can be useful to know whether a value is expressible in JSON without actually serializing it.

To install:

npm install json-expressible

To use:

var jsonExpressible = require("json-expressible");

// The following return true

console.log(jsonExpressible("abc"));
console.log(jsonExpressible(123));
console.log(jsonExpressible(true));
console.log(jsonExpressible(null));
console.log(jsonExpressible({ abc: "def" }));
console.log(jsonExpressible([1, 2, 3]));


// The following return false

console.log(jsonExpressible(undefined));
console.log(jsonExpressible(NaN));
console.log(jsonExpressible(function () {}));
console.log(jsonExpressible(new Date()));
console.log(jsonExpressible(Infinity));
console.log(jsonExpressible(/reg.ex/));

console.log(jsonExpressible([ undefined ]));
console.log(jsonExpressible({ abc: undefined }));

var circularObject = {};
circularObject.ref = circularObject;
console.log(jsonExpressible(circularObject));

var circularArray = [];
circularArray.push(circularArray);
console.log(jsonExpressible(circularArray));