可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试):

问题:

A bunch of code isn't working and I'm trying to identify where the problem lies but console.log() isn't logging any results in Chrome Dev tools, am I doing it correctly?

$(window).scroll(function() {
       $('section').each(function(){
            var id='#'+$(this).attr('id'),
                off=$(id).offset().top,
                hei=$(id).height(),
                winscroll=$(window).scrollTop(),
                dif=hei+off-($(window).height());

            if (winscroll >= off && winscroll<=dif) {
                console.log('first broken');
                $(id+' .sticky').removeClass('abs').addClass('fix');
            } else if (winscroll > dif){
                console.log('second broken');
                $(id+' .sticky').removeClass('fix').addClass('abs');
            } else {
                console.log('third broken');
                $(id+' .sticky').removeClass('fix abs');
            }   });
        });

EDIT FULL CODE ADDED

$(document).ready(function() {

    // If a browser supports 3D transforms use the fancy menu if it doesn't, use standard accordion menu instead
    if($('html').hasClass('csstransforms3d')){

        $( "#mp-menu" ).removeClass( "snap-drawers" ).addClass( "mp-menu" );

        $('nav ul li ul').css('border-bottom','1px solid rgba(255, 255, 255, .05)');
        $('nav ul li ul').css('background','none');

        // Insert elements where necessary to create the right structure
        $('#mp-menu').wrapInner('<div class="mp-level" />');
        $('#mp-menu').find('li > ul').wrap('<div class="mp-level" />');

        $("#mp-menu ul li .mp-level").prepend(function () {
            return '<span class="menu-title">' + $(this).prev().text() + '</span> <a class="ico mp-back" href="#">Back</a>';
        });

        // load in necessary JS files
        $.getScript('http://176.32.230.2/baodev.com/cjo/wp-content/themes/CJO/js/multi-level-menu.js');

    } else {

        // load in necessary JS files
        $.getScript( "http://176.32.230.2/baodev.com/cjo/wp-content/themes/CJO/js/jquery.navgoco.min.js", function() {
            $("#demo1").navgoco({accordion: true});
        });

        $.getScript( "http://176.32.230.2/baodev.com/cjo/wp-content/themes/CJO/js/snap.min.js", function() {

            // Snapper settings     
            var snapper = new Snap({
              element: document.getElementById('scroller'),
              disable: 'right',
              maxPosition: 291
            });

            var addEvent = function addEvent(element, eventName, func) {
                if (element.addEventListener) {
                return element.addEventListener(eventName, func, false);
              } else if (element.attachEvent) {
                  return element.attachEvent("on" + eventName, func);
              }
            };

            // Toggle button
            addEvent(document.getElementById('trigger'), 'click', function(){
                if( snapper.state().state=="left" ){
                    snapper.close();
                    $( ".menu-trigger" ).removeClass( "active" );
                } else {
                    snapper.open('left');
                    $( ".menu-trigger" ).addClass( "active" );
                }
            });

            addEvent(document.getElementById('scroller'), 'click', function(){
                if( snapper.state().state=="left" ){
                    $( ".menu-trigger" ).removeClass( "active" );
                }
            });

            /* Prevent Safari opening links when viewing as a Mobile App */
            (function (a, b, c) {
              if(c in b && b[c]) {
                  var d, e = a.location,
                      f = /^(a|html)$/i;
                  a.addEventListener("click", function (a) {
                      d = a.target;
                      while(!f.test(d.nodeName)) d = d.parentNode;
                      "href" in d && (d.href.indexOf("http") || ~d.href.indexOf(e.host)) && (a.preventDefault(), e.href = d.href)
                  }, !1)
              }
            })(document, window.navigator, "standalone");

        });

    } // end if

    fitHeight();

    $(window).scroll(function() {
        $('section').each(function(){
            var id='#'+$(this).attr('id'),
                off=$(id).offset().top,
                hei=$(id).height(),
                winscroll=$(window).scrollTop(),
                dif=hei+off-($(window).height());

           console.log('msj');

            if (winscroll >= off && winscroll<=dif) {
                $(id+' .sticky').removeClass('abs').addClass('fix');
            } else if (winscroll > dif){
                $(id+' .sticky').removeClass('fix').addClass('abs');
            } else {
                $(id+' .sticky').removeClass('fix abs');
            }
        });
     });

});

// Trigger FitHeight on browser resize
$(window).resize(fitHeight);

EDIT

Some bits of the full code (above) refer to other JS files and code returns no errors when run with these files present. After troubleshooting I see the console message before the scroll function but I do not see the console message within the scroll function.

fitHeight();

    console.log('About to bind scroll effects'); // I SEE THIS MESSAGE

    $(window).scroll(function() {

        console.log("scroll bound, now loop through sections"); //BUT NOT THIS ONE

        $('section').each(function(){

回答1:

Sounds like you've either hidden JavaScript logs or specified that you only want to see Errors or Warnings. Open Chrome's Developer Tools and go to the Console tab. At the bottom you want to ensure that JavaScript is ticked and also ensure that you have "All", "Logs" or "Debug" selected.

In the image above I have JavaScript, Network, Logging, CSS and Other ticked and "All" selected.

Another potential problem could be that your $(window).scroll() function isn't wrapped within a .ready() function (as documented here):

$(document).ready(function() {
    $(window).scroll(function() {
        ...
    });
});

When pasting your code into JSFiddle and giving some dummy content, your code works perfectly fine: JSFiddle demo.

Edit:

The question was edited. The new code given throws two errors:

Uncaught ReferenceError: fitHeight is not defined Uncaught TypeError: Cannot read property 'addEventListener' of null

Because of this, the code stops execution prior to reaching any console.log call.

回答2:

In my case, all console messages were not showing because I had left a string in the "filter" textbox.

Remove the filter it by clicking the X as shown:

回答3:

I feel a bit stupid on this but let this be a lesson to everyone...Make sure you target the right selector!

Basically the console wasn't logging anything because this particular code snippet was attempting to grab the scrolling area of my window, when in fact my code was setup differently to scroll an entire DIV instead. As soon as I changed:

$(window).scroll(function() {

to this:

$('#scroller').scroll(function() {

The console started logging the correct messages.

回答4:

In my case I was developing a Polymer WebComponent, which is included using <link rel="import"> into the main HTML document. Turns out that the WebComponent HTML file was being cached for some reason, even though I had changed it since the cached version.

To solve it I opened the Developer Console (in Chrome), right clicked on the reload arrow next to the URL bar and selected "Empty cache and hard reload" - problem solved.

回答5:

Consider a more pragmatic approach to the question of "doing it correctly".

console.log("about to bind scroll fx");

$(window).scroll(function() {

       console.log("scroll bound, loop through div's");

       $('div').each(function(){

If both of those logs output correctly, then its likely the problem exists in your var declaration. To debug that, consider breaking it out into several lines:

var id='#'+$(this).attr('id');

console.log(id);

var off=$(id).offset().top;
var hei=$(id).height();
var winscroll=$(window).scrollTop();
var dif=hei+off-($(window).height());

By doing this, at least during debugging, you may find that the var id is undefined, causing errors throughout the rest of the code. Is it possible some of your div tags do not have id's?

回答6:

Just you need to select right option to show the log messages from the option provided in left side under the console tab. You can refer the screen shot.

回答7:

You may have used the filter function in the console which will hide anything that doesn't match your query. Remove the query and your messages will display.