javascript - 将一个数组中的值插入多维数组并出现错误

Question

function studentClasses() {
    var names = [];
    var course = [];
    var sortCourse = [];
    var uniqueCourse = [];
    var nameCourse = [];

    while (records.readNextRecord()) {
        var studentNames = records.getStudentName();
        var studentCourse = records.getStudentCourseNumber();

        names.push(studentNames);
        course.push(studentCourse);
        sortCourse.push(studentCourse);
        sortCourse.sort();
    }
    // sort a list of courses to find the unique courses
    for (var i = 0; i < sortCourse.length; i++) {
        if (sortCourse[i] !== sortCourse[i - 1]) {
            uniqueCourse.push(sortCourse[i]);
        }
    }

    uniqueCourse.sort;
    nameCourse.length = uniqueCourse.length;

    // create multi-d array containing names for a certain course
    for (var x = 0; x < uniqueCourse.length; x++) {
        for (var y = 0; y < course.length; y++) {
            if (uniqueCourse[x] === course[y]) {
                nameCourse[x].push(names[y]);
            }
        }
    }
}

这是我正在处理的代码，我收到错误

Uncaught TypeError: Cannot read property 'push' of undefined(…)

我有两个数组(“类(class)”和“名称”)，其中包含特定索引中包含数据的信息。我正在尝试将“uniqueCourse”数组中的信息与“course”数组进行比较，如果它们匹配，则“course”中的索引位置"然后将用于从“names”中的索引位置调用信息。

问题出在这里: 当我尝试将“names[y]”插入长度等于 uniqueCourse(如果运行代码则为 5)的多维数组时，出现错误。

问题: 为什么当我尝试使用代码时会收到未定义的错误

nameCourse[x].push(names[y]);

将信息从names推送到nameCourse，其中x是我希望存储这些名称的相应级别？

我想要:

nameCourse = [ [however many names called from names[y]],
               [however many names called from names[y]],
               [however many names called from names[y]],
               [however many names called from names[y]],
               [however many names called from names[y]] ]

Answer 1

您的 nameCourse 数组已填充 undefined 您需要将 nameCourse[x] 初始化为数组，然后才将其插入其中。 如下所示:

nameCourse = new Array(uniqueCourse.length).fill(0);