javascript - 无法读取未定义的值 'visibility' - J

Question

我正在使用 jQuery。每当调用 menu.tog 函数时，它似乎忘记了“this”(菜单)是什么。我还尝试在函数中将“this”替换为“menu”。

    var usn = $("#userstuff");
var menu = $('#userinfo');

menu.height('0px');

menu.tog=function()
{
if (menu.css('visibility','hidden')=='hidden')
    menu.css('visibility','visible');
else
    menu.css('visibility','hidden');
}

Answer 1

这应该有效:

// only use 'menu', not '$(menu)' and don't write 'px'
// or in one row: var menu = $('#userinfo').height(0);
var menu = $('#userinfo');
menu.height(0);

// however your `tog` function is called, there may be not referenced
// to 'this', instead use 'menu'
// but keep in mind, 'menu' is a jQuery object here, not a DOM element
menu.tog = function() {
    if ( menu.css("visibility") == "hidden" ) {
        menu.css("visibility", "visible");
    }
    else {
        menu.css("visibility", "hidden");
    }

    // or in one line too:
    // menu.css("visibility", menu.css("visibility") == "hidden" ? "visible" : "hidden");
};

menu.tog();