For of is used to iterate over the property values, instead of property names which is for in loop.
For in loop prints property name. See below example
Written in venilla js
var arr = [1, 2, 3, 4, 5, 6];
arr.obj = 'I am a string';
for (var i in arr) {
console.log(i); //print 0 1 2 3 4 5 obj, property names
}For of loop prints property values.
var arr = [1, 2, 3, 4, 5, 6];
arr.obj = 'I am a string';
for (var i of arr) {
console.log(i); //print 1 2 3 4 5 6, values not property name
}