Jquery $(this) not working inside function

问题

I am trying to use waypoints.js to have elements fadein when scrolling to hit the elements.

I have

$(document).ready(function(){

$('.card').waypoint(function(down) {
    console.log('hit element');
    $(this).addClass('card-fadeIn');
}, { offset: '100%' });

});

What this does is adds the class 'card-fadeIn' which is opacity 1 and an ease in animation.

When I change it to

$('.card').addClass('card-fadeIn');

It works fine, but adds opacity 1 to every card class and ruins the fadein effect. I was trying to use $(this) instead but it wont fadein, nor will it give an error in the console. Any ideas why?

回答1:

You have to use

$(this.element)

in a Waypoint handler. So,

$(this.element).addClass('card-fadeIn');

should do what you want.

$(this) works inside jQuery callbacks because jQuery is designed for things to work that way. There's nothing magic about it, however, so if this doesn't refer to a DOM element, you'll get a jQuery object that won't do anything (and which won't report any errors, because, again, that's just how jQuery works). The Waypoint library binds this to its own context object, and that exposes a reference to the DOM element involved in the callback as the "element" property.

回答2:

Have you tried this.element?

$(document).ready(function(){

$('.card').waypoint(function(down) {
    console.log('hit element');
    $(this.element).addClass('card-fadeIn');
}, { offset: '100%' });

});

来源：https://stackoverflow.com/questions/31968289/jquery-this-not-working-inside-function