Serialization #

Math.js has a number of data types like Matrix, Complex, and Unit. These types are instantiated JavaScript objects. To be able to store these data types or send them between processes, they must be serialized. The data types of math.js can be serialized to JSON. Use cases:

• Store data in a database or on disk.
• Interchange of data between a server and a client.
• Interchange of data between a web worker and the browser.

Math.js types can be serialized using JavaScript’s built-in JSON.stringify function:

const x = math.complex('2 + 3i')
const str = JSON.stringify(x, math.replacer)
console.log(str)
// outputs a string '{"mathjs":"Complex","re":2,"im":3}'

IMPORTANT: in most cases works, serialization correctly without passing the math.replacer function as second argument. This is because in most cases we can rely on the default behavior of JSON.stringify, which uses the .toJSON method on classes like Unit and Complex to correctly serialize them. However, there are a few special cases like the number Infinity which does require the replacer function in order to be serialized without losing information: without it, Infinity will be serialized as "null" and cannot be deserialized correctly.

So, it’s best to always pass the math.replacer function to prevent weird edge cases.

In order to deserialize a string, containing math.js data types, JSON.parse can be used. In order to recognize the data types of math.js, JSON.parse must be called with the reviver function of math.js:

const json = '{"mathjs":"Unit","value":5,"unit":"cm","fixPrefix":false}'
const x = JSON.parse(json, math.reviver)   // Unit 5 cm

Note that if math.js is used in conjunction with other data types, it is possible to use multiple reviver functions at the same time by cascading them:

const reviver = function (key, value) {
  return reviver1(key, reviver2(key, value))
}