mathjs/src/json/replacer.js

import { factory } from '../utils/factory.js'

const name = 'replacer'
const dependencies = []

export const createReplacer = /* #__PURE__ */ factory(name, dependencies, () => {
  /**
   * Stringify data types into their JSON representation.
   * Most data types can be serialized using their `.toJSON` method,
   * but not all, for example the number `Infinity`. For these cases you have
   * to use the replacer. Example usage:
   *
   *     JSON.stringify([2, Infinity], math.replacer)
   *
   * @param {string} key
   * @param {*} value
   * @returns {*} Returns the replaced object
   */
  return function replacer (key, value) {
    // the numeric values Infinitiy, -Infinity, and NaN cannot be serialized to JSON
    if (typeof value === 'number' && (!isFinite(value) || isNaN(value))) {
      return {
        mathjs: 'number',
        value: String(value)
      }
    }

    if (typeof value === 'bigint') {
      return {
        mathjs: 'bigint',
        value: String(value)
      }
    }

    return value
  }
})