javascript - How can I refresh an array? - Stack Overflow

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With this function I create a list:

var array = [];
var oldarray = [];


function port1() {
    oldarray.push('Port '+parseFloat(document.getElementsByClassName(mylist.name)[1].getAttribute('id'))+': '+mylist.name);
    document.getElementById('text').textContent = array;
    $.each(oldarray, function(i, el){
        if($.inArray(el, array) === -1) array.push(el);
    });
}

I want to let the newest entries be add to the last index of the array, and the oldest at the start of the array. And if one entry is ing again, it should appear only once in the array but the index has to "refresh" so that this entry is again at the last position of the array.

With this function I create a list:

var array = [];
var oldarray = [];


function port1() {
    oldarray.push('Port '+parseFloat(document.getElementsByClassName(mylist.name)[1].getAttribute('id'))+': '+mylist.name);
    document.getElementById('text').textContent = array;
    $.each(oldarray, function(i, el){
        if($.inArray(el, array) === -1) array.push(el);
    });
}

I want to let the newest entries be add to the last index of the array, and the oldest at the start of the array. And if one entry is ing again, it should appear only once in the array but the index has to "refresh" so that this entry is again at the last position of the array.

• javascript
• jquery
• arrays

Share Improve this question Follow edited Oct 10, 2018 at 7:32 cнŝdk 32.2k77 gold badges6060 silver badges8080 bronze badges asked Oct 10, 2018 at 7:18 user10441435user10441435 2

• So if an entry to be added is already in the array, it should be moved to the last position in the array? – AKX Commented Oct 10, 2018 at 7:25
• Yes, and I want them later to delete the oldest entry – user10441435 Commented Oct 10, 2018 at 7:27

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 3

You can test over the existence of the element in the array and if it does, remove it and push it in the end, otherwise just push it.

This is how should be your function:

function port1(arr, el) {
  let ind = arr.indexOf(el);
  if (ind > -1)
    arr.splice(ind, 1);
  arr.push(el);
}

Demo:

This is a working demo:

var array = [12, 5, 3, 6];

function port1(arr, el) {
  let ind = arr.indexOf(el);
  if (ind > -1)
    arr.splice(ind, 1);
  arr.push(el);
}

port1(array, 4);
port1(array, 5);
port1(array, 12);

console.log(array);

Something like

function addEntry(array, entry) {
    var entryIndex = array.indexOf(entry);
    if(entryIndex > -1) {
        array.splice(entryIndex, 1);  // Remove the entry from its original position.
    }
    array.push(entry);  // Add to the end of the array.
}

var array = ['Hello', 'World'];
console.log(array);
addEntry(array, 'This is new');
console.log(array);
addEntry(array, 'Hello');
console.log(array);

should work for you. This example outputs

[ 'Hello', 'World' ]
[ 'Hello', 'World', 'This is new' ]
[ 'World', 'This is new', 'Hello' ]

Note that the array is changed in-place.

thank you for your help, your solutions really helped me. I tried also this solution and it seems to work. Maybe not the best and finest solution, but I wanted to add this one. Tank's! :)

var array = ['bye bye', 'hello guys', 'good morning'];
    var entry = 'bye bye';
    if (array.includes(entry)) {
        array.splice(array.indexOf(entry),1);
        array.push(entry);
    }

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