这个jQuery / Regex代码段到底在做什么？

Question

I'm not very good with RegEx, and am trying to learn. I have inherited a project which contains the following line of code:

function findCourseIdFromForm(where) {
    var matchRegex = /\[course-[0-9]*\]/;
    var replaceRegex = /\[|\]|[a-z]|\-/g;
    return $(".cnumber", where.parent()).attr("name").match( matchRegex )[0].replace( replaceRegex,"" );
}

I'm not entirely sure what this piece of code is trying to do, but I know that it is causing issues on my page. I'm using jQuery validator and this specific component (".cnumber") is causing the validation to fail and I'm not entirely sure why, so some insight into this line is appreciated.

The .cnumber field in the HTML looks like this:

<input type="hidden" name="courses[course-0][cnumber]" class="cnumber" />

Answer 1

它从标记中的名称属性中删除[ ， ] ，小写字母和- ，大概是返回课程号。

Answer 2

It just get the course number. In you example, it return 0

Answer 3

This function takes where node, gets its parent, finds .cnumber node within the parent, then takes [course-0] part and finally remove all [ , ] , - , and lowercase letters.

So the function returns the number that stands after [course- part, or empty string if there is no number