jquery determines whether the scrollbar reaches the top and bottom of the window

<script type= "Text/javascript" >$ (document). Ready (function () {    alert ($ (window). Height ()); The browser window currently has a visible area height of     alert ($ (document). Height ()); The height of the window document in the browser     alert ($ (document.body). Height ());//browser Current window document body altitude      alert ($ (document.body). Outerheight (True));//browser window The total height of the document body includes border padding margin    Alert ($ (window). width ()); The browser window currently has a viewable area width of     alert ($ (document). width ());//browser window document for image width      Alert ($ (document.body). width ());//browser Current window document body height     alert ($ (document.body). Outerwidth ( true);//browser window The total width of the document body includes border padding margin        var win_height=$ ( window). Height ();    var doc_height=$ (document). Height ();    var scroll_top=$ ( Document). ScrollTop ();       /*    doc_height is the height of the documentation, Scroll_ Top is the height of the scroll bar above the top of the document, Window_heighT indicates the height of the window.      when scroll_top = 0 o'clock, indicates that the scroll bar has reached the top of the window.      when Scroll_top + window_height >= doc_height, the scroll bar has reached the bottom of the window.     */    //Determines whether the scrollbar reaches the bottom of the window     $ (Windows). Bind (' scroll ', function ( ) {   //Bind scrolling event         if ($ (document). ScrollTop () + $ (window). Height () >= $ (document). Height ()) {            console.log (win_height);             console.log ($ (document). ScrollTop ());             console.log (doc_height);            //......       }    });   }) ;</script>

jquery determines whether the scrollbar reaches the top and bottom of the window