将<a>附加到<li>麻烦中

I am simply trying to append an a-tag into a li, but for some reason I cannot see why this doesn't work.

navListItem = '<li class="p-list-item"></li>';                
mainLink = '<a class="main-a" href="' + item.link + '"><span>"' + item.title + '"</span></a>'; 
$(navListItem).append(mainLink);

Your navListItem does not exist yet.

append it to another html element first and change the last line to:

$(".p-list-item").append(mainLink);

Seems legit and work for me.

Did you append the navListItem to a real html-element in the DOM?

$(document.body).append(navListItem);

You need something to append it to

var item = {
    link:"javascript:void(0)",
    title: "title"
};
navListItem = '<li class="p-list-item"></li>';                
mainLink = '<a class="main-a" href="' + item.link + '"><span>"' + item.title + '"</span></a>';
var z = $(navListItem).append(mainLink);

$("#container").append(z);

here is a jsfiddle http://jsfiddle.net/6vy5efeu/