1var array = [
2  {name: "John", age: 34},
3  {name: "Peter", age: 54},
4  {name: "Jake", age: 25}
5];
6
7array.sort(function(a, b) {
8  return a.age - b.age;
9}); // Sort youngest first

1const books = [
2  {id: 1, name: 'The Lord of the Rings'},
3  {id: 2, name: 'A Tale of Two Cities'},
4  {id: 3, name: 'Don Quixote'},
5  {id: 4, name: 'The Hobbit'}
6]
7
8compareObjects(object1, object2, key) {
9  const obj1 = object1[key].toUpperCase()
10  const obj2 = object2[key].toUpperCase()
11
12  if (obj1 < obj2) {
13    return -1
14  }
15  if (obj1 > obj2) {
16    return 1
17  }
18  return 0
19}
20
21books.sort((book1, book2) => {
22  return compareObjects(book1, book2, 'name')
23})
24
25// Result:
26// {id: 2, name: 'A Tale of Two Cities'}
27// {id: 3, name: 'Don Quixote'}
28// {id: 4, name: 'The Hobbit'}
29// {id: 1, name: 'The Lord of the Rings'}

1function compareFirstNames( a, b ) {
2  if ( a.first_name < b.first_name ){
3    return -1;
4  }
5  if ( a.first_name > b.first_name ){
6    return 1;
7  }
8  return 0;
9}
10
11var people =[
12    {"first_name":"Carol", "age":29},
13    {"first_name":"Anna", "age":32},
14    {"first_name":"Bob", "age":32}
15];
16
17people.sort( compareFirstNames ); //people is now sorted by first name from a-z

1function sortByDate( a, b ) {
2  if ( a.created_at < b.created_at ){
3    return -1;
4  }
5  if ( a.created_at > b.created_at ){
6    return 1;
7  }
8  return 0;
9}
10
11myDates.sort(sortByDate);//myDates is not sorted.

1items.sort(function(a, b) { 
2  return a.id - b.id  ||  a.name.localeCompare(b.name);
3});
4