问题
I am trying to clean up the way my anchors work. I have a header that is fixed to the top of the page, so when you link to an anchor elsewhere in the page, the page jumps so the anchor is at the top of the page, leaving the content behind the fixed header (I hope that makes sense). I need a way to offset the anchor by the 25px from the height of the header. I would prefer HTML or CSS, but Javascript would be acceptable as well.
回答1:
You could just use CSS without any javascript.
Give your anchor a class:
<a class="anchor" id="top"></a>
You can then position the anchor an offset higher or lower than where it actually appears on the page, by making it a block element and relatively positioning it. -250px will position the anchor up 250px
a.anchor {
display: block;
position: relative;
top: -250px;
visibility: hidden;
}
回答2:
I found this solution:
<a name="myanchor">
<h1 style="padding-top: 40px; margin-top: -40px;">My anchor</h1>
</a>
This doesn't create any gap in the content and anchor links works really nice.
回答3:
As this is a concern of presentation, a pure CSS solution would be ideal. However, this question was posed in 2012, and although relative positioning / negative margin solutions have been suggested, these approaches seem rather hacky, create potential flow issues, and cannot respond dynamically to changes in the DOM / viewport.
With that in mind I believe that using JavaScript is still (February 2017) the best approach. Below is a vanilla-JS solution which will respond both to anchor clicks and resolve the page hash on load (See JSFiddle). Modify the .getFixedOffset() method if dynamic calculations are required. If you're using jQuery, here's a modified solution with better event delegation and smooth scrolling.
(function(document, history, location) {
var HISTORY_SUPPORT = !!(history && history.pushState);
var anchorScrolls = {
ANCHOR_REGEX: /^#[^ ]+$/,
OFFSET_HEIGHT_PX: 50,
/**
* Establish events, and fix initial scroll position if a hash is provided.
*/
init: function() {
this.scrollToCurrent();
window.addEventListener('hashchange', this.scrollToCurrent.bind(this));
document.body.addEventListener('click', this.delegateAnchors.bind(this));
},
/**
* Return the offset amount to deduct from the normal scroll position.
* Modify as appropriate to allow for dynamic calculations
*/
getFixedOffset: function() {
return this.OFFSET_HEIGHT_PX;
},
/**
* If the provided href is an anchor which resolves to an element on the
* page, scroll to it.
* @param {String} href
* @return {Boolean} - Was the href an anchor.
*/
scrollIfAnchor: function(href, pushToHistory) {
var match, rect, anchorOffset;
if(!this.ANCHOR_REGEX.test(href)) {
return false;
}
match = document.getElementById(href.slice(1));
if(match) {
rect = match.getBoundingClientRect();
anchorOffset = window.pageYOffset + rect.top - this.getFixedOffset();
window.scrollTo(window.pageXOffset, anchorOffset);
// Add the state to history as-per normal anchor links
if(HISTORY_SUPPORT && pushToHistory) {
history.pushState({}, document.title, location.pathname + href);
}
}
return !!match;
},
/**
* Attempt to scroll to the current location's hash.
*/
scrollToCurrent: function() {
this.scrollIfAnchor(window.location.hash);
},
/**
* If the click event's target was an anchor, fix the scroll position.
*/
delegateAnchors: function(e) {
var elem = e.target;
if(
elem.nodeName === 'A' &&
this.scrollIfAnchor(elem.getAttribute('href'), true)
) {
e.preventDefault();
}
}
};
window.addEventListener(
'DOMContentLoaded', anchorScrolls.init.bind(anchorScrolls)
);
})(window.document, window.history, window.location);
回答4:
I was looking for a solution to this as well. In my case, it was pretty easy.
I have a list menu with all the links:
<ul>
<li><a href="#one">one</a></li>
<li><a href="#two">two</a></li>
<li><a href="#three">three</a></li>
<li><a href="#four">four</a></li>
</ul>
And below that the headings where it should go to.
<h3>one</h3>
<p>text here</p>
<h3>two</h3>
<p>text here</p>
<h3>three</h3>
<p>text here</p>
<h3>four</h3>
<p>text here</p>
Now because I have a fixed menu at the top of my page I can't just make it go to my tag because that would be behind the menu.
Instead, I put a span tag inside my tag with the proper id.
<h3><span id="one"></span>one</h3>
Now use 2 lines of CSS to position them properly.
h3{ position:relative; }
h3 span{ position:absolute; top:-200px;}
Change the top value to match the height of your fixed header (or more). Now I assume this would work with other elements as well.
回答5:
FWIW this worked for me:
[id]::before {
content: '';
display: block;
height: 75px;
margin-top: -75px;
visibility: hidden;
}
回答6:
Pure css solution inspired by Alexander Savin:
a[name] {
padding-top: 40px;
margin-top: -40px;
display: inline-block; /* required for webkit browsers */
}
Optionally you may want to add the following if the target is still off the screen:
vertical-align: top;
回答7:
My solution combines the target and before selectors for our CMS. Other techniques don't account for text in the anchor. Adjust the height and the negative margin to the offset you need...
:target::before {
content: '';
display: block;
height: 180px;
margin-top: -180px;
}
回答8:
This takes many elements from previous answers and combines into a tiny (194 bytes minified) anonymous jQuery function. Adjust fixedElementHeight for the height of your menu or blocking element.
(function($, window) {
var adjustAnchor = function() {
var $anchor = $(':target'),
fixedElementHeight = 100;
if ($anchor.length > 0) {
$('html, body')
.stop()
.animate({
scrollTop: $anchor.offset().top - fixedElementHeight
}, 200);
}
};
$(window).on('hashchange load', function() {
adjustAnchor();
});
})(jQuery, window);
If you don't like the animation, replace
$('html, body')
.stop()
.animate({
scrollTop: $anchor.offset().top - fixedElementHeight
}, 200);
with:
window.scrollTo(0, $anchor.offset().top - fixedElementHeight);
Uglified version:
!function(o,n){var t=function(){var n=o(":target"),t=100;n.length>0&&o("html, body").stop().animate({scrollTop:n.offset().top-t},200)};o(n).on("hashchange load",function(){t()})}(jQuery,window);
回答9:
I had been facing a similar issue, unfortunately after implementing all the solutions above, I came to the following conclusion.
- My inner elements had a fragile CSS structure and implementing a position relative / absolute play, was completely breaking the page design.
- CSS is not my strong suit.
I wrote this simple scrolling js, that accounts for the offset caused due to the header and relocated the div about 125 pixels below. Please use it as you see fit.
The HTML
<div id="#anchor"></div> <!-- #anchor here is the anchor tag which is on your URL -->
The JavaScript
$(function() {
$('a[href*=#]:not([href=#])').click(function() {
if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'')
&& location.hostname == this.hostname) {
var target = $(this.hash);
target = target.length ? target : $('[name=' + this.hash.slice(1) +']');
if (target.length) {
$('html,body').animate({
scrollTop: target.offset().top - 125 //offsets for fixed header
}, 1000);
return false;
}
}
});
//Executed on page load with URL containing an anchor tag.
if($(location.href.split("#")[1])) {
var target = $('#'+location.href.split("#")[1]);
if (target.length) {
$('html,body').animate({
scrollTop: target.offset().top - 125 //offset height of header here too.
}, 1000);
return false;
}
}
});
See a live implementation here.
回答10:
For modern browsers, just add the CSS3 :target selector to the page. This will apply to all the anchors automatically.
:target {
display: block;
position: relative;
top: -100px;
visibility: hidden;
}
回答11:
You can do it without js and without altering html. It´s css-only.
a[id]::before {
content: '';
display: block;
height: 50px;
margin: -30px 0 0;
}
That will append a pseudo-element before every a-tag with an id. Adjust values to match the height of your header.
回答12:
As @moeffju suggests, this can be achieved with CSS. The issue I ran into (which I'm surprised I haven't seen discussed) is the trick of overlapping previous elements with padding or a transparent border prevents hover and click actions at the bottom of those sections because the following one comes higher in the z-order.
The best fix I found was to place section content in a div that is at z-index: 1:
// Apply to elements that serve as anchors
.offset-anchor {
border-top: 75px solid transparent;
margin: -75px 0 0;
-webkit-background-clip: padding-box;
-moz-background-clip: padding;
background-clip: padding-box;
}
// Because offset-anchor causes sections to overlap the bottom of previous ones,
// we need to put content higher so links aren't blocked by the transparent border.
.container {
position: relative;
z-index: 1;
}
回答13:
Solutions with changing position property are not always possible (it can destroy layout) therefore I suggest this:
HTML:
<a id="top">Anchor</a>
CSS:
#top {
margin-top: -250px;
padding-top: 250px;
}
Use this:
<a id="top"> </a>
to minimize overlapping, and set font-size to 1px. Empty anchor will not work in some browsers.
回答14:
For the same issue, I used an easy solution : put a padding-top of 40px on each anchor.
回答15:
Borrowing some of the code from an answer given at this link (no author is specified), you can include a nice smooth-scroll effect to the anchor, while making it stop at -60px above the anchor, fitting nicely underneath the fixed bootstrap navigation bar (requires jQuery):
$(".dropdown-menu a[href^='#']").on('click', function(e) {
// prevent default anchor click behavior
e.preventDefault();
// animate
$('html, body').animate({
scrollTop: $(this.hash).offset().top - 60
}, 300, function(){
});
});
回答16:
The above methods don't work very well if your anchor is a table element or within a table (row or cell).
I had to use javascript and bind to the window hashchange event to work around this (demo):
function moveUnderNav() {
var $el, h = window.location.hash;
if (h) {
$el = $(h);
if ($el.length && $el.closest('table').length) {
$('body').scrollTop( $el.closest('table, tr').position().top - 26 );
}
}
}
$(window)
.load(function () {
moveUnderNav();
})
.on('hashchange', function () {
moveUnderNav();
});
* Note: The hashchange event is not available in all browsers.
回答17:
I ran into this same issue and ended up handling the click events manually, like:
$('#mynav a').click(() ->
$('html, body').animate({
scrollTop: $($(this).attr('href')).offset().top - 40
}, 200
return false
)
Scroll animation optional, of course.
回答18:
Instead of having a fixed-position navbar which is underlapped by the rest of the content of the page (with the whole page body being scrollable), consider instead having a non-scrollable body with a static navbar and then having the page content in an absolutely-positioned scrollable div below.
That is, have HTML like this...
<div class="static-navbar">NAVBAR</div>
<div class="scrollable-content">
<p>Bla bla bla</p>
<p>Yadda yadda yadda</p>
<p>Mary had a little lamb</p>
<h2 id="stuff-i-want-to-link-to">Stuff</h2>
<p>More nonsense</p>
</div>
... and CSS like this:
.static-navbar {
height: 100px;
}
.scrollable-content {
position: absolute;
top: 100px;
bottom: 0;
overflow-y: scroll;
width: 100%;
}
This achieves the desired result in a straightforward, non-hacky way. The only difference in behaviour between this and some of the clever CSS hacks suggested above are that the scrollbar (in browsers that render one) will be attached to the content div rather than the whole height of the page. You may or may not consider this desirable.
Here's a JSFiddle demonstrating this in action.
回答19:
You can achieve this without an ID using the a[name]:not([href]) css selector. This simply looks for links with a name and no href e.g. <a name="anc1"></a>
An example rule might be:
a[name]:not([href]){
display: block;
position: relative;
top: -100px;
visibility: hidden;
}
回答20:
This was inspired by the answer by Shouvik - same concept as his, only the size of the fixed header isn't hard coded. As long as your fixed header is in the first header node, this should "just work"
/*jslint browser: true, plusplus: true, regexp: true */
function anchorScroll(fragment) {
"use strict";
var amount, ttarget;
amount = $('header').height();
ttarget = $('#' + fragment);
$('html,body').animate({ scrollTop: ttarget.offset().top - amount }, 250);
return false;
}
function outsideToHash() {
"use strict";
var fragment;
if (window.location.hash) {
fragment = window.location.hash.substring(1);
anchorScroll(fragment);
}
}
function insideToHash(nnode) {
"use strict";
var fragment;
fragment = $(nnode).attr('href').substring(1);
anchorScroll(fragment);
}
$(document).ready(function () {
"use strict";
$("a[href^='#']").bind('click', function () {insideToHash(this); });
outsideToHash();
});
回答21:
I'm facing this problem in a TYPO3 website, where all "Content Elements" are wrapped with something like:
<div id="c1234" class="contentElement">...</div>
and i changed the rendering so it renders like this:
<div id="c1234" class="anchor"></div>
<div class="contentElement">...</div>
And this CSS:
.anchor{
position: relative;
top: -50px;
}
The fixed topbar being 40px high, now the anchors work again and start 10px under the topbar.
Only drawback of this technique is you can no longer use :target.
回答22:
Adding to Ziav's answer (with thanks to Alexander Savin), I need to be using the old-school <a name="...">...</a> as we're using <div id="...">...</div> for another purpose in our code. I had some display issues using display: inline-block -- the first line of every <p> element was turning out to be slightly right-indented (on both Webkit and Firefox browsers). I ended up trying other display values and display: table-caption works perfectly for me.
.anchor {
padding-top: 60px;
margin-top: -60px;
display: table-caption;
}
回答23:
I added 40px-height .vspace element holding the anchor before each of my h1 elements.
<div class="vspace" id="gherkin"></div>
<div class="page-header">
<h1>Gherkin</h1>
</div>
In the CSS:
.vspace { height: 40px;}
It's working great and the space is not chocking.
回答24:
how about hidden span tags with linkable IDs that provide the height of the navbar:
#head1 {
padding-top: 60px;
height: 0px;
visibility: hidden;
}
<span class="head1">somecontent</span>
<h5 id="headline1">This Headline is not obscured</h5>
heres the fiddle: http://jsfiddle.net/N6f2f/7
回答25:
You can also add an anchor with follow attr:
(text-indent:-99999px;)
visibility: hidden;
position:absolute;
top:-80px;
and give the parent container a position relative.
Works perfect for me.
回答26:
A further twist to the excellent answer from @Jan is to incorporate this into the #uberbar fixed header, which uses jQuery (or MooTools). (http://davidwalsh.name/persistent-header-opacity)
I've tweaked the code so the the top of the content is always below not under the fixed header and also added the anchors from @Jan again making sure that the anchors are always positioned below the fixed header.
The CSS:
#uberbar {
border-bottom:1px solid #0000cc;
position:fixed;
top:0;
left:0;
z-index:2000;
width:100%;
}
a.anchor {
display: block;
position: relative;
visibility: hidden;
}
The jQuery (including tweaks to both the #uberbar and the anchor approaches:
<script type="text/javascript">
$(document).ready(function() {
(function() {
//settings
var fadeSpeed = 200, fadeTo = 0.85, topDistance = 30;
var topbarME = function() { $('#uberbar').fadeTo(fadeSpeed,1); }, topbarML = function() { $('#uberbar').fadeTo(fadeSpeed,fadeTo); };
var inside = false;
//do
$(window).scroll(function() {
position = $(window).scrollTop();
if(position > topDistance && !inside) {
//add events
topbarML();
$('#uberbar').bind('mouseenter',topbarME);
$('#uberbar').bind('mouseleave',topbarML);
inside = true;
}
else if (position < topDistance){
topbarME();
$('#uberbar').unbind('mouseenter',topbarME);
$('#uberbar').unbind('mouseleave',topbarML);
inside = false;
}
});
$('#content').css({'margin-top': $('#uberbar').outerHeight(true)});
$('a.anchor').css({'top': - $('#uberbar').outerHeight(true)});
})();
});
</script>
And finally the HTML:
<div id="uberbar">
<!--CONTENT OF FIXED HEADER-->
</div>
....
<div id="content">
<!--MAIN CONTENT-->
....
<a class="anchor" id="anchor1"></a>
....
<a class="anchor" id="anchor2"></a>
....
</div>
Maybe this is useful to somebody who likes the #uberbar fading dixed header!
回答27:
@AlexanderSavin's solution works great in WebKit browsers for me.
I additionally had to use :target pseudo-class which applies style to the selected anchor to adjust padding in FF, Opera & IE9:
a:target {
padding-top: 40px
}
Note that this style is not for Chrome / Safari so you'll probably have to use css-hacks, conditional comments etc.
Also I'd like to notice that Alexander's solution works due to the fact that targeted element is inline. If you don't want link you could simply change display property:
<div id="myanchor" style="display: inline">
<h1 style="padding-top: 40px; margin-top: -40px;">My anchor</h1>
</div>
回答28:
Here's the solution that we use on our site. Adjust the headerHeight variable to whatever your header height is. Add the js-scroll class to the anchor that should scroll on click.
// SCROLL ON CLICK
// --------------------------------------------------------------------------
$('.js-scroll').click(function(){
var headerHeight = 60;
$('html, body').animate({
scrollTop: $( $.attr(this, 'href') ).offset().top - headerHeight
}, 500);
return false;
});
来源：https://stackoverflow.com/questions/9047703/fixed-position-navbar-obscures-anchors