splice first added object in an array when new element is added in javascript

Question

i am working on splicing the old object ie first added object in an array when new element(object) is added in to it automatically.

this is the sample code i worked on

  var sampleArr = [{"id":4,"hostName":"henry"},
                    {"id":3,"hostName":"jeff"},
                      {"id":2,"hostName":"mark"},
                        {"id":1,"hostName":"holder"}];

the above array contains 4 objects when 5 object( {"id":5,"hostName":"punk"}) is added i want to splice first added object ie( {"id":1,"hostName":"holder"}).

here is what i tried in controller

for( var i=0; i<sampleArr.length; i++){
          var index = i;
          if(sampleArr.length > 4){
            sampleArr.splice(index,1,sampleArr[i]);

        } 
        }

but it not working as i expected. please any help me to sought out this!

No need of loop `if (arr.length === 4) { arr[0] = newObj; }` — Tushar, Oct 07 '16 at 04:18
`splice` can do many things. Can you show us what output you expect? — LinuxDisciple, Oct 07 '16 at 04:21
var sampleArr = [{"id":4,"hostName":"henry"}, {"id":3,"hostName":"jeff"}, {"id":2,"hostName":"mark"}, {"id":5,"hostName":"punk"}]; — Sukumar MS, Oct 07 '16 at 04:23
If you were looking for a more... thorough solution, perhaps consider something like http://stackoverflow.com/questions/1583123/circular-buffer-in-javascript? — Shadowen, Oct 07 '16 at 04:30
do you want first element to remove or the last one coz' {"id":1,"hostName":"holder"} is last element and {"id":4,"hostName":"henry"} is first one. — A.T., Oct 07 '16 at 05:13

score 1 · Accepted Answer · answered Oct 07 '16 at 04:22

1

You can use the simple pop() to take out the last element and use push to add a new element into the array!

var sampleArr = [{
  "id": 4,
  "hostName": "henry"
}, {
  "id": 3,
  "hostName": "jeff"
}, {
  "id": 2,
  "hostName": "mark"
}, {
  "id": 1,
  "hostName": "holder"
}];



sampleArr.pop()

sampleArr.push({
  "id": 5,
  "hostName": "punk"
})

console.log(sampleArr)

answered Oct 07 '16 at 04:22

Pranesh Ravi

18,642
9
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@SukumarDhoni Of course you can. https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/push – Pranesh Ravi Oct 07 '16 at 04:42
can i push like this sampleArr.push(sampleArr[sampleArr[5]]); – Sukumar MS Oct 07 '16 at 04:45

score 1 · Answer 2 · edited May 23 '17 at 11:53

1

You can use unshift to add new item in begin of array and use pop to remove last item in array. Read more here.

Try this:

sampleArr.unshift({"id":5,"hostName":"punk"});
sampleArr.pop();

Hope will helps.

edited May 23 '17 at 11:53

Community

1
1

answered Oct 07 '16 at 04:26

DieuNQ

975
1
7
11

See also http://stackoverflow.com/a/33608379/5195629 for an implementation that wraps this in a function (fairly simple really, but I wanted to include it for completeness). – Shadowen Oct 07 '16 at 04:32

score 1 · Answer 3 · answered Oct 07 '16 at 05:10

I think OP is asking for FIFO (first in first out operation) , since I don't understand how {"id":1,"hostName":"holder"} could be first element in below array. But here is what I suggest.

Array.prototype.performFIFO = function(element) { this.push(element); this.shift(); return this; } 

var sampleArr = [{"id":4,"hostName":"henry"},
                    {"id":3,"hostName":"jeff"},
                      {"id":2,"hostName":"mark"},
                        {"id":1,"hostName":"holder"}];



sampleArr.performFIFO({"id":5,"hostName":"fifth element"})

console.log(sampleArr)

score 0 · Answer 4 · edited Oct 10 '16 at 16:43

0

Try this:

sampleArr.splice(sampleArr.length,1,sampleArr[i]);

edited Oct 10 '16 at 16:43

Vojtech Ruzicka

16,384
15
63
66

answered Oct 07 '16 at 04:35

splice first added object in an array when new element is added in javascript

this is the sample code i worked on

here is what i tried in controller

4 Answers4