Question

我有以下javascript代码，问题是首先执行了函数getBestMovies4BestPCRating();并且在amovies.forEach(function(item) {之后

任何想法？

document.getElementById('sendMovies').addEventListener('click', function() {
    var movieIDs = document.getElementById('MovieIDs').value;
    var data = {};
    var amovies = {};
    var movies = {};

    data["movieList"] = '[' + movieIDs + ']';

    params = JSON.stringify(data);

    var http = new XMLHttpRequest();

    var url = "http://............."
    http.open("POST", url, true);

    //Send the proper header information along with the request
    http.setRequestHeader("Content-type", "application/json");

    http.onreadystatechange = function() { //Call a function when the state changes.
        if (http.readyState == 4 && http.status == 200) {
            movies = http.responseText;
            amovies = JSON.parse(movies);

            amovies.forEach(function(item) {
                if (item.rating > 4) {
                    getEntitiesRatings(item.ratingsPK.userId, 0);
                }
            });
            getBestMovies4BestPCRating();
            convertmovies2table(bestMovies);
        }
    }
    http.send(params);

});

function getEntitiesRatings(userid, kind) {

    var xmlhttp = new XMLHttpRequest();
    var url = " http://.............entities.ratings/" + userid;

    xmlhttp.onreadystatechange = function() {
        if (this.readyState == 4 && this.status == 200) {
            var myArr = JSON.parse(this.responseText);
            if (kind == 0) {
                computeUserColleration(myArr, userid);
            }
            if (kind == 1) {
                bestUserMovies(myArr, userid);
            }
        }
    };
    xmlhttp.open("GET", url, true);
    xmlhttp.send();

}

Answer 1

按照您编写的顺序执行这些功能。但是，第一个函数是异步的，因此结果不会立即可用。

请考虑使用Promise。

另外，尝试下次提供一个最小的例子。代码中不需要所有这个集群来表达你的麻烦。

Javascript onreadystatechange函数调用优先级

1 个答案: