javascript - After the jquery object is defined as a jquery variable, how to use: gt this (there may be a problem with the expression)

Question

$("li:gt(2)") can be used, but a long time ago I saw a jquery variable converted to XX and then used:gt(2), such as var $li=$(" li"), I need to use: gt(2) based on the $li variable. I don’t know if you understand what I mean. I am looking for an answer. I saw it on a blog a long time ago, but I can’t remember it.

Answer 1

$li.filter(':gt(2)')

Is this so?

Answer 2

jquery itself does not have this method, only this selector, but you can extend it

$.fn.gt = function(num){
    var after = [];
    this.each(function(i){
        if(i>=num){
           after.push(this);
        }
    });
    return after;
}
$.fn.lt = function(num){
    var before = [];
    this.each(function(i){
        if(i<num){
           before.push(this);
        }
    });
    return before;
}