JavaScript equivalent of jQuery's extend method

Question

Background

I have a function that takes a config object as an argument. Within the function, I also have default object. Each of those

Answer 1

You can use Object.assign.

var defaults = {key1: "default1", key2: "default2", key3: "defaults3"};
var config = {key1: "value1"};

var settings = Object.assign({}, defaults, config); // values in config override values in defaults
console.log(settings); // Object {key1: "value1", key2: "default2", key3: "defaults3"}

It copies the values of all enumerable own properties from one or more source objects to a target object and returns the target object.

Object.assign(target, ...sources)

It works in all desktop browsers except IE (but including Edge). It has mitigated mobile support.

See for yourself here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign

About deep copy

However, Object.assign does not have the deep option that jQuery's extend method have.

Note: you can generally use JSON for a similar effect though

var config = {key1: "value1"};
    var defaults = {key1: "default1", key2: "default2", keyDeep: {
        kd1: "default3",
        kd2: "default4"
    }};
    var settings = JSON.parse(JSON.stringify(Object.assign({}, defaults, config))); 
    console.log(settings.keyDeep); // Object {kd1: "default3", kd2: "default4"}