writing a loop inside of an object code example

Example 1: javascript iterate over object

var obj = { first: "John", last: "Doe" };

Object.keys(obj).forEach(function(key) {
    console.log(key, obj[key]);
});

Example 2: javascript loop object

let obj = {
  key1: "value1",
  key2: "value2",
  key3: "value3"
}

Object.keys(obj).forEach(key => {
    console.log(key, obj[key]);
});
// key1 value1
// key2 value2
// key3 value3

// using for in - same output as above
for (let key in obj) {
  let value = obj[key];
  console.log(key, value);
}