Cố định header khi cuộn trang

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In this tutorial, we’ll learn how khổng lồ create a pattern seen on many websites these days: a fixed header which animates khổng lồ a less obtrusive sầu state as we scroll down the page. We’ll start with the basic structure, then get things working using CSS & pure JavaScript. Before closing, we’ll briefly cover how we can optimize our code as well as discussing challenges present when applying this kind of pattern khổng lồ touch devices.

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To get an idea of what we’re going lớn build, here’s the demo (you may prefer fullscreen view):

HTML Markup

We’ll start this exercise with the following markup–a header, containing a và a couple of other nested elements:

Logo ☰ The nav element, which is part of the header, contains three elements; the logo, the main thực đơn, and a placeholder button lớn trigger a responsive sầu thực đơn (below 1061px). 

Note: If you click on this button, nothing much will happen. Creating the responsive sầu thực đơn is beyond the scope of this tutorial.

Initial CSS Styles

Now let’s have sầu a look at some CSS styles to get things moving:

header position: fixed; top: 0; width: 100%; padding: 20px; box-sizing: border-box; background: #DD3543;nav display: flex; align-items: flex-end; justify-content: space-between; transition: align-items .2s;.hình ảnh font-size: 2rem; display: inline-block; padding: 20px 30px; background: #F35B66; color: #fff; margin: 50px 0 0 50px; transition: all .2s;ul display: flex; margin: 50px 50px 0 0; padding: 0; transition: margin .2s;li:not(:last-child) margin-right: 20px;li a display: block; padding: 10px 20px;.toggle-menu display: none; font-size: 2rem; color: #fff; margin: 10px 10px 0 0; transition: margin .2s;main display: block; padding: 0 20px;Here’s a brief explanation of the most important rules here:

The header element is a fixed positioned element.We use flexbox to lớn layout the nav element.The biệu tượng công ty has margin-top: 50px and margin-left: 50px. Additionally, we give it padding: 20px 30px.The main menu mirrors the hình ảnh sản phẩm, with margin-top: 50px and margin-right: 50px.The responsive sầu link button is hidden. It becomes visible when the viewport width is less than 1061px. Moreover, we set its top and right margins to 10px.We add the transition property to the elements whose property values will change in the future. In this way, we achieve sầu a smooth transition effect between the initial state và the final state. 

With these rules in place, the header looks like this:


Animating the Header

So far we’ve sầu built the basic structure of our header. It’s now time to discuss the next steps:

The main element should be positioned right underneath the header. Remember that the header has positioned: fixed, and it’s therefore positioned on top of the main element. The header should be animated as we scroll down the page.

To solve the first task, we add a padding-top property to lớn the main element. The value of this property should be equal to the header’s height. In our case, we haven’t specified a fixed height for our header, so we’ll use some JavaScript to lớn calculate it, và then add the corresponding padding to lớn the main element. 

To solve sầu the second task, we’ll do the following:

Retrieve sầu the number of pixels that the document has already been scrolled vertically.If this number is greater than 150px, we assign the scroll class to lớn the header.


Here’s the required JavaScript code–we begin by defining some variables, calculating the height of the header, then adding that value as padding-top khổng lồ the main element:

var m = document.querySelector("main"), h = document.querySelector("header"), hHeight;function setTopPadding() hHeight = h.offsetHeight; m.style.paddingTop = hHeight + "px";For this demonstration, we use the offsetHeight property lớn retrieve sầu the header’s height. Keep in mind that we could equally have sầu used the getBoundingClientRect() method. It’s worth mentioning that this method may return fractional values.

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Now onto lớn the scrolling event:

function onScroll() window.addEventListener("scroll", callbackFunc); function callbackFunc() var y = window.pageYOffset; if (y > 150) h.classList.add("scroll"); else h.classList.remove("scroll"); Here we take advantage of the window’s pageYOffset property lớn calculate the number of pixels that our document has been scrolled vertically. cảnh báo that this property doesn’t work in older versions of IE (here.

Then we use the classList property khổng lồ add & remove the scroll class from our header. Not all browsers support this property however, so if you want lớn tư vấn any of these you may want to lớn look at the classList.js and classie.js polyfills. For this example, we could have used the className property lớn manipulate our single class, but in a real-world scenario this might not the ikhuyến mãi solution (in case we have multiple classes). 

To wrap things up, we hotline our functions in two different cases:

When the page loadsand as we reform size the browser window.

window.onload = function() setTopPadding(); onScroll();;window.onreform size = function() setTopPadding();;


As long as our scrolling exceeds the limit of 150px, a few additional CSS rules take place:

.scroll box-shadow: 0 7px 0 0 rgba(0, 0, 0, .1);.scroll .hình ảnh sản phẩm padding: 10px 20px; font-size: 1.5rem;.scroll nav align-items: center;.scroll .hình ảnh,.scroll ul,.scroll .toggle-menu margin: 0;Specifically, we make the following changes:

Add a light gray box shadow khổng lồ the header.Reduce the logo’s padding và phông kích cỡ.Change the alignment for the flex items across the cross-axis.Remove sầu the margin from the hình ảnh sản phẩm, the thực đơn, và the responsive sầu liên kết button.

The aforementioned rules result in this new header layout:


Going Responsive

As we’ve mentioned in a previous section, when the viewport width is less than 1061px, we hide the menu and show the responsive sầu link button (which doesn’t actually vì anything). Plus, we make a few other changes in the target elements.