未捕获的类型错误:无法读取未定义的属性“top" [英] Uncaught TypeError: Cannot read property 'top' of undefined
问题描述
如果这个问题已经得到回答,我深表歉意.我试过寻找解决方案,但找不到任何适合我的代码的解决方案.我还是 jQuery 的新手.
I apologize if this question has already been answered. I've tried searching for solutions but could not find any that suited my code. I'm still new to jQuery.
对于两个不同的页面,我有两种不同类型的粘性菜单.这是两者的代码.
I have two different types of sticky menus for two different pages. Here's the code for both.
$(document).ready(function () {
var contentNav = $('.content-nav').offset().top;
var stickyNav = function () {
var scrollTop = $(window).scrollTop();
if (scrollTop > contentNav) {
$('.content-nav').addClass('content-nav-sticky');
} else {;
$('.content-nav').removeClass('content-nav-sticky')
}
};
stickyNav();
$(window).scroll(function () {
stickyNav();
});
});
$(document).ready(function () {
var stickyNavTop = $('.nav-map').offset().top;
// var contentNav = $('.content-nav').offset().top;
var stickyNav = function () {
var scrollTop = $(window).scrollTop();
if (scrollTop > stickyNavTop) {
$('.nav-map').addClass('sticky');
// $('.content-nav').addClass('sticky');
} else {
$('.nav-map').removeClass('sticky');
// $('.content-nav').removeClass('sticky')
}
};
stickyNav();
$(window).scroll(function () {
stickyNav();
});
});
我的问题是底部粘性侧边菜单的代码不起作用,因为第二行代码 var contentNav = $('.content-nav').offset().top;
会触发一个错误,内容为未捕获的类型错误:无法读取未定义的属性 'top'".事实上,第二行下面的其他 jQuery 代码根本无法工作,除非它们被放置在它上面.
My problem is that the code for the sticky side menu on the bottom doesn't work because the second line of code var contentNav = $('.content-nav').offset().top;
fires a error that reads "Uncaught TypeError: Cannot read property 'top' of undefined". In fact, no other jQuery code below that second line works at all unless they are placed above it.
经过一番研究,我认为问题在于 $('.content-nav').offset().top
找不到指定的选择器,因为它位于不同的页面上.如果是这样,我找不到解决方案.
After some researching, I think the problem is that $('.content-nav').offset().top
can't find the specified selector because it's on a different page. If so, I can't find a solution.
推荐答案
在尝试获取其偏移量之前检查 jQuery 对象是否包含任何元素:
Check if the jQuery object contains any element before you try to get its offset:
var nav = $('.content-nav');
if (nav.length) {
var contentNav = nav.offset().top;
...continue to set up the menu
}
这篇关于未捕获的类型错误:无法读取未定义的属性“top"的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!