Data type for an array of Object in realm - react-native realm

I'm using realm for Javascript using React-native

I want to generate a realm schema to hold an array of Object as this:

arrayOfObj:[{ key1:1111, key2:2222, key3:333 }]

What I have tried so far is using the mixed type in my schema

const mySchema = {
    name: "mySchema",
    properties: {
        _id: "objectId",
        arrOfObj: "mixed" //'have used mixed[] too but they all don't work
    }
}

I have tried using mixed and also using mixed[] but when I try to insert the array of object i get the error: mySchema.arrOfObj must be of type 'mixed?[]', got 'object' ([object Object])].

Now, What is the correct data type for the array of object in realm?

const myScheme = {
  name: "myScheme",
  primaryKey: "_id",
  properties: {
   _id: "objectId",
   _partition: "string",
   name: "string",
   tasks: "myData[]"
 }
};

const myData = {
  name: "myData",
  primaryKey: "_id",
  properties: {
    _id: "objectId",
    _partition: "string",
    firstname: "string",
    lastname: "string",
 }

};