Serialization of RegExp

Question

So, I was interested to find that JSON.stringify reduces a RegExp to an empty object-literal (fiddle):

JSON.stringify(/^[0-9]+$/) // \"{}\"
         


        

Answer 1

Both JSON.stringify and JSON.parse can be customized to do custom serialization and deserialization by using the replacer and reviver arguments.

var o = {
  foo: "bar",
  re: /foo/gi
};

function replacer(key, value) {
  if (value instanceof RegExp)
    return ("__REGEXP " + value.toString());
  else
    return value;
}

function reviver(key, value) {
  if (value.toString().indexOf("__REGEXP ") == 0) {
    var m = value.split("__REGEXP ")[1].match(/\/(.*)\/(.*)?/);
    return new RegExp(m[1], m[2] || "");
  } else
    return value;
}

console.log(JSON.parse(JSON.stringify(o, replacer, 2), reviver));

You just have to come up with your own serialization format.