对object数组进行排序，然后使用if setText

var arr = [
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 30 },
  { name: 'Charlie', age: 20 }
];

arr.sort(function(a, b) {
  return a.age - b.age;
});

console.log(arr);

[
  { name: 'Charlie', age: 20 },
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 30 }
]

var sortedArr = [
  { name: 'Charlie', age: 20 },
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 30 }
];

if (sortedArr.length > 0) {
  var firstObj = sortedArr[0];
  var text = firstObj.name + ' is the youngest with age ' + firstObj.age;
  setText(text);
} else {
  setText('No objects in the array');
}