Update a specific value of an object which is inside an array-CodePudding

So im building an app mock up , upon sending a message I need to notify all the participants of the chat that they have an unread message, My participant type has a field called "unread" which is an array of objects like such

unread:[
{chatId:'13213', msgs:3},
{chatId:'132546', msgs:1}
];

chat id references to a unique conversation, and msgs number shows new messages sent , the length of msgs array is the number of unread msgs you have , what I want to do is , when a new msg is sent I want to loop through the unread array and

condition one Array is completely empty :

add an object to it

condition two array already has objects, then find the one that has the same chatId as the one I will pass in the function and increase the message count

condition three, array already has objects but not with the chatId I provided, in which case create a new object and add it to an existing array.

any ideas on how I can go about this?

I tried doing the following but it doesn't work

emp.unread.length < 1
              ? [{ chatId: chatId, unread: 1 }]
              : emp.unread.map((cht) => {
                  if (cht.chatId === chatId) {
                    return {
                      ...emp.unread,
                      chatId: chatId,
                      unread: cht.unread   1,
                    };
                  } else {
                    return { ...emp.unread, chatId: chatId, unread: 1 };
                  }
                }),

CodePudding user response：

You can try using the if condition as below:

You can use filter/find to complete you tasks normally.There could still be other less resource consuming way but this way you will get your task done.

if(unread.length == 0 ){
//pushing the object
}else{

if(chechExistingChat(chatid)){
addOnExistingChat(chatId)
}

else{
//unread.push(new object)
}

}


function checkExistingChat(chatId){
let sameChatArray = unread.filter((item)=>{
return item.chatId == chatId
})
return !!sameChatArray.length
}

function addOnExistingChat(chatId){
 let finalArray = unread.map((item)=>{
    if(item.chatId == chatId){
   return {...item,msgs:item.msgs 1}
      }
    return item
   })
  return finalArray
}