在 JavaScript 中使用 array.push() 后数组长度不正确

Question

Fellow noob in JavaScript so forgive me if I'm missing something basic.

I have an array that I want to push data retrieved from an AJAX request using JQuery, where CalendarEvent is a custom class I created.

let events=[];
$.post(url, data, function(data) {
  data.forEach(x => function(x) {
    let event = new CalendarEvent();
    events.push(event);
  });
}, "json");

My question is when I try to console.log(events) inside the function(data) method, it shows up as the correct amount of objects. When I console.log(events) outside of the method (nothing else added or subtracted), the length is 0 and all my objects are inside an empty array. The first 2 lines in screenshot are console.log(events) outside the method, the second 2 lines are inside the method (I also don't know why they aren't showing in order). Can anyone help me fix my problem?

Console.log Console.log arrays expanded

Answer 1

In javascript all methods regular methods are called BEFORE any async code so what is happening is that your console log outside the code is happening BEFORE the method is ran, run any code that depends on the information in the ajax call inside of the method OR you can wrap any functions you need ran after that by using setTimeout().

watch a talk on the event loop; it helped me understand what is going on here, this was really confusing to me when I first started but understanding the event loop helped.