default()

A function can be provided that returns the default value used for this property, like:

import {DefineMap} from "can";

const Example = DefineMap.extend( {
  prop: {
    default: function() {
      return [];
    }
  }
} );

const ex = new Example();
console.log( ex.prop.serialize() ); //-> []

If the default value should be an object of some type, it should be specified as the return value of a function (the above call signature) so that all instances of this map don't point to the same object. For example, if the property value above had not returned an empty array but instead just specified an array using the next call signature below, all instances of that map would point to the same array (because JavaScript passes objects by reference).

default

Any value can be provided as the default value used for this property, like:

import {DefineMap} from "can"

const Example = DefineMap.extend( {
  prop: {
    default: "foo"
  }
} );

const ex = new Example();
console.log( ex.prop ); //-> "foo"

import {DefineMap} from "can";


const Person = DefineMap.extend( {
  // A default age of `0`:
    age: {
        default: 0
    },
  // A default address:
    address: {
        default() {
            return { city: "Chicago", state: "IL" };
        }
    }
} );

const person = new Person();
console.log( person.age ); //-> 0
console.log( person.address.serialize() ); //-> { city: "Chicago", state: "IL" }