Why jQuery 3.0 Hides Errors and How to Catch Them with Promises

jQuery introduced a major change in version 3.0: the ready handler now returns a Promise. If you simply write

$(function(){ throw new Error('出错了'); $('#container').html('你好'); })

, the error is swallowed and the page shows no content, while the console remains silent.

In contrast, using jQuery 2.1.3 the same code triggers a visible error in the console, making debugging easier.

Because jQuery 3.0 officially supports Promise , you can handle errors by chaining $.ready().then(...).fail(...). For example:

$.ready().then(function() {
    throw new Error('出错了');
    $('#container').html('你好');
}).fail(function(error) {
    throw error;
});

Now the console correctly displays the error message.