How would I set up a method to update passed properties of JavaScript object?

Question

I'm looking to create a method for an object to update only the properties that are passed.

for example

function Car () {
  this.color = 'yellow'
  this.brand = 'bmw'
  this.key = 0

  this.update = function (o) {
    this.key++
    // maybe Object.assign(this, o) somehow ??
  }
}

If I do Car.update({color:'red'}) I want to update the object but not overwrite the brand. I want to use something like Object.assign(this, o) but not sure how to assign it. Do I need to create a prototype? Car.prototype.update = ?

Answer 1

Object.assign mutates the first argument, so there is no need to assign the result of Object.assign() to something.

Object.assign(this, o);

...will work fine.

function Car () {
  this.color = 'yellow'
  this.brand = 'bmw'
  this.key = 0

  this.update = function (o) {
    this.key++
    Object.assign(this, o);
  }
}

var car = new Car();
car.update({color: 'red'});
console.log(car);