Question

使用push()方法后，我将项目arr[i].title打印到控制台中，它显示“未定义”，而不是＆＃34;上帝父亲1＆＃34;。见代码第12行。

以下是代码：

<!doctype html>
<html lang="en">
<head>
    <title> Document Object Properties </title>
    <meta charset="utf-8">
    <script>
        window.onload = init;
        function init() {
            var arr = [];
            for (var i=0; i < 3; i++) {
                arr.push(new Movie("God father " + i,1970,"Cowboy",15,["13:00","17:00","21:00"]));
                console.log("Array item: " + arr[i].title); // WHY Undefined???
                for (var j=0; j < 3; j++) {
                    //arr[i].showtimes[j] = "0" + i + ":00";
                }
            }
            var div = document.getElementById("result");
            div.innerHTML = 
                "Movie: " + arr[0].title + "<br>" +
                "Year: " + arr[0].year + "<br>" +
                "Genre: " + arr[0].genre;
        }

        function Movie(title,year,genre,rating,showtimes) {
            var title= " ";
            var year= 2000;
            var genre= " ";
            var rating= 15;
            var showtimes= [];
        }
    </script>
</head>
<body>
    <div id="result">
    </div>       
</body>
</html>

Answer 1

您没有在对象构造函数中创建任何属性，只是用值覆盖参数。

您想获取参数并输入属性：

function Movie(title,year,genre,rating,showtimes) {
  this.title = title;
  this.year = year;
  this.genre = genre;
  this.rating = rating;
  this.showtimes = showtimes;
}

Answer 2

您在var内使用Movie创建变量，但这不是您向对象添加属性的方式。您必须将值分配给this。

function Movie(title, year, genre, rating, showtimes) {
    this.title = title;
    this.year = year;
    // etc
}

为什么无法通过实例化构造函数方法将对象推入数组？

2 个答案: