How do I extend jQuery's selector engine to warn me when a selector is not found?

问题

Say I make a mistake when I'm trying to find an element and I make a typo, like $('lsdkfj'). Instead of jQuery returning me an empty array, I'd like to return an error message in the console, like "The selector 'lsdkfj' cannot be found". What is the best way to go about doing this?

回答1:

Like this:

var oldInit = $.fn.init;
$.fn.init = function(selector, context, rootjQuery) {
    var result = new oldInit(selector, context, rootjQuery);
    if (result.length === 0)
        console.info("jQuery call has no elements!", arguments);
    return result;
};

来源：https://stackoverflow.com/questions/5744997/how-do-i-extend-jquerys-selector-engine-to-warn-me-when-a-selector-is-not-found