how to add a key and value to a object code example

Example 1: js add key to object

// given
const obj = {
    key1: value1,
    key2: value2
};

// add pair
obj["key3"] = value3;
obj.key4 = value4;

Example 2: add new key value pair to object javascript

const person = {
	name: "Elon Musk"
}

person.age = 49;

console.log(person);
// {name: "Elon Musk", age: 49}