Why did the global variable array become empty outside the function?

  • 0
    There is a small script on node.js that first receives an array of id, then mixes them up, then searches for people's names by id and writes a new array.
    But by declaring the global variable arrName, it is impossible to display this array, or rather it is empty for some reason.

    function shuffle(array) {
        array.sort(() => Math.random() - 0.5);
    const arrName = [];
    const XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest;
    const x = new XMLHttpRequest();
    x.open('GET', 'https://slack.com/api/conversations.members?token=xxx&channel=xxx');
    x.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
    x.onload = function() {
        let array_1 = JSON.parse(this.responseText).members;
        var array_cleaned = array_1.filter(function(element) {
            return element.length <= 9;
        var array_cleaned2 = array_cleaned.filter(function(element2) {
            const y = new XMLHttpRequest();
            y.open('GET', 'https://slack.com/api/users.profile.get?token=xxx&user=' + element2);
            y.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
            y.onload = function() {
            let array_2 = JSON.parse(this.responseText).profile.display_name;
                console.log('В группе состоит ' + array_2);

    Why console.log (arrName);
    outputs just an empty array?
    Moreover, if I check arrName after the line "arrName.push (array_2);" , then the array is output (which is logical 3 times)
    JavaScript Paige Bullock, Dec 18, 2019

  • 2 Answers
  • 0
    Asynchronous requests.

    console.log (arrName) - displayed before everything in array_cleaned2 is executed

  • 0
    Because you fill it inside the callback, which at the time of the output console.log (arrName)

    has not been called yet.

    Put the output after the line

    arrName.push (array_2);

    to make sure that an empty array is displayed first, and then it starts filling
    Paige Calderon

Your Answer
To place the code, please use CodePen or similar tool. Thanks you!