let arr = [
  {name: "John", age: 30},
  {name: "Grin", age: 10},
  {name: "Marie", age: 50},
];

//An array showing persons with age less than 40 
//is given by the following syntax

let newArr = arr.filter(name=>name.age < 40));

console.log(newArray);   // => [{name: "John", age: 30}, {name: "Grin", age: 10},]