let arrObj = [{name: 'aaa', age: 11}, {name: 'bbb', age: 22}, {name: 'ccc', age: 33}]
for(let i in arrObj){
console.log("i:", i); // i: 0 i: 1 i: 2
}
for(let i of arrObj){
console.log("i:", i); // i: {name: 'aaa', age: 11} i: {name: 'bbb', age: 22} i: {name: 'ccc', age: 33}
}