Reliable way to check if objects is serializable in JavaScript

Question

Is there a known way or a library that already has a helper for assessing whether an object is serializable in JavaScript?

I tried the following but it doesn't cover prototype properties so it provides false positives:

_.isEqual(obj, JSON.parse(JSON.stringify(obj))

There's another lodash function that might get me closer to the truth, _.isPlainObject. However, while _.isPlainObject(new MyClass()) returns false, _.isPlainObject({x: new MyClass()}) returns true, so it needs to be applied recursively.

Before I venture by myself on this, does anybody know an already reliable way for checking if JSON.parse(JSON.stringify(obj)) will actually result in the same object as obj?

Answer 1

function isSerializable(obj) {
  var isNestedSerializable;
  function isPlain(val) {
    return (typeof val === 'undefined' || typeof val === 'string' || typeof val === 'boolean' || typeof val === 'number' || Array.isArray(val) || _.isPlainObject(val));
  }
  if (!isPlain(obj)) {
    return false;
  }
  for (var property in obj) {
    if (obj.hasOwnProperty(property)) {
      if (!isPlain(obj[property])) {
        return false;
      }
      if (typeof obj[property] == "object") {
        isNestedSerializable = isSerializable(obj[property]);
        if (!isNestedSerializable) {
          return false;
        }
      }
    }
  }
  return true;
}

Recursively iterating over all of given object properties. They can be either:

• plain objects ("an object created by the Object constructor or one with a [[Prototype]] of null." - from lodash documentation)
• arrays
• strings, numbers, booleans
• undefined

Any other value anywhere within passed obj will cause it to be understood as "un-serializable".

(To be honest I'm not absolutely positive that I didn't omit check for some serializable/non-serializable data types, which actually I think depends on the definition of "serializable" - any comments and suggestions will be welcome.)