Arrays comparison or best method to add new elements

Question

I have a webservice in json that returns me the last people who passed in a certain location.

That said I did the following:

• I only ask for the api always the information of the last person to pass on site.

• I created on my in page setInterval of 1s to read this api and make a prepend with the information of this json on the screen within a div.

Done this I noticed that there is a problem. When several people pass in less than 1s I lose or better I skip the display of some people on the screen.

I set by default the api to always return the last 9 people to me so I need to compare the box ids that are already on the screen with the ids that come from json and know which Ids don’t have on the screen so I can include these people in the prepend. Could someone assist me in this question of knowing which ids exist in an array 1 that do not exist in array 2 ?

---

I made a code according to the help below but it is returning

setInterval(function() {    
    var api = [],tela = [];
    $(".cardface").each(function(){
        tela.push($(this).attr('idimg'));
    });

    $.getJSON('<?php url(); ?>/rtffeed', function(data) {
        $.each(data, function(key,val){
            api.push(val.id_imagens);
        });        
    });


    var adicionar = $(api).not(tela).get();

    console.log(adicionar);

}, 1000);

whereas if I do

console.log(tela);

he returns {317,318} and I do

console.log(api);

he returns {322,321,319,318,317,316,315,314,313}

then the add should be {322,321,319,316,315,314,313}

but he’s coming back blank

screen, api, add in this order

Answer 1

Pose to do so if you like, testing if one element does not exist in the other:

var json = [9,8,7,6,5,4,3,2,1];           // elementos à adicionar
var tela = [4,2];                         // elementos já adicionados

var adicionar = $(json).not(tela).get();  // retorna os que não derão match

console.log(String(adicionar));           // Resultado em forma de String
console.log(adicionar);                   // Resultado em forma de Array

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