how to get last object from array and remains parent array same in javascript

Question

Hi I have an array with a messages key which have multiple objects, i want to remove all objects except the last object in the messages array

I have example array below :

const array = [
    {
      messages: [
        { content: "abc", id: "message01" },
        { content: "def", id: "message02" },
        { content: "ghi", id: "message03" }
      ],
      user: "user 1",
      participants: ["user1", "user2"],
      id: "chat01"
    },
    {
      messages: [
        { content: "hello", id: "message01" },
        { content: "hi", id: "message02" },
        { content: "How are you", id: "message03" }
      ],
      user: "user 2",
      participants: ["user1", "user2"],
      id: "chat02"
    }
  ];

my excepted array below:

const expectedArray = [
    {
      messages: [{ content: "ghi", id: "message03" }],
      user: "user 1",
      participants: ["user1", "user2"],
      id: "chat01"
    },
    {
      messages: [{ content: "How are you", id: "message03" }],
      user: "user 2",
      participants: ["user1", "user2"],
      id: "chat02"
    }
  ];

Answer 1

const array = [
    {
      messages: [
        { content: "abc", id: "message01" },
        { content: "def", id: "message02" },
        { content: "ghi", id: "message03" }
      ],
      user: "user 1",
      participants: ["user1", "user2"],
      id: "chat01"
    },
    {
      messages: [
        { content: "hello", id: "message01" },
        { content: "hi", id: "message02" },
        { content: "How are you", id: "message03" }
      ],
      user: "user 2",
      participants: ["user1", "user2"],
      id: "chat02"
    }
  ];
  
  for (let i = 0; i < array.length; i++) {
    array[i].messages = new Array (array[i].messages[array[i].messages.length -1])
}

  
  console.log (array)

Answer 2

const array = [
    {
      messages: [
        { content: "abc", id: "message01" },
        { content: "def", id: "message02" },
        { content: "ghi", id: "message03" }
      ],
      user: "user 1",
      participants: ["user1", "user2"],
      id: "chat01"
    },
    {
      messages: [
        { content: "hello", id: "message01" },
        { content: "hi", id: "message02" },
        { content: "How are you", id: "message03" }
      ],
      user: "user 2",
      participants: ["user1", "user2"],
      id: "chat02"
    }
  ];
  

/** slice() method gets the last element of the array. 
If we provide negative index -1 to it
then it will remove the last item and
return it as a new array.
We overwrite messages array with the
return value of the slice() method which
is a new array containing only the last
element of the original messages array.
*/
array.forEach(e => e.messages = e.messages.slice(-1))

console.log(array)