loop through objects in javascript list code example

Example 1: javascript iterate object

let person={
 	first_name:"johnny",
  	last_name: "johnson",
	phone:"703-3424-1111"
};
for (let i in person) {
  let t = person[i]
  	console.log(i,":",t);
}

Example 2: how to loop through an array of objects+

var arr = [[1,2], [3,4], [5,6]];
 for (var i=0; i < arr.length; i++) {
  for (var j=0; j < arr[i].length; j++) {
    console.log(arr[i][j]);
  }
}