find() will look for elements with class classname within the div element.
filter() filters out elements whose class is classname.
Basically, find sub-elements are found, and filter is a level search.
·The find function is to query the sub-elements of the current object collection;
·The filter function is to query the current object collection Filter and use filter conditions to narrow the scope;
·The parameter of the find function is a jQuery selector expression; The parameter of
·filter is also a selector expression, but there can be multiple conditions, separated by commas (logical OR relationship);
·The parameter of filter can also be a function. When calling the function, the index parameter will be automatically passed in. The function needs to return true or false to select or exclude elements.