for loop on length of object code example

Example 1: js loop over array of objects extract value

var myArr = [{name: 'rich', secondName: 'james'}, {name: 'brian', secondName: 'chris'}];

var mySecondArr = myArr.map(x => x.name);
console.log(mySecondArr);

Example 2: iterate object js

for (let key in yourobject) {
   if (yourobject.hasOwnProperty(key)) {
      console.log(key, yourobject[key]);
   }
}