在javascript中，你可以做:

var element = document.getElementById("myid");
element.style.position = "fixed";
element.style.top = "0%";

这是另一种选择:

JAVASCRIPT

var initTopPosition= $('#myElementToStick').offset().top;   
$(window).scroll(function(){
    if($(window).scrollTop() > initTopPosition)
        $('#myElementToStick').css({'position':'fixed','top':'0px'});
    else
        $('#myElementToStick').css({'position':'absolute','top':initTopPosition+'px'});
});

你的#myElementToStick应该以position:absolute CSS属性开始。

我的解决方案有点啰嗦，但它处理变量定位从左边缘居中布局。

// Ensurs that a element (usually a div) stays on the screen
//   aElementToStick   = The jQuery selector for the element to keep visible
global.makeSticky = function (aElementToStick) {
    var $elementToStick = $(aElementToStick);
    var top = $elementToStick.offset().top;
    var origPosition = $elementToStick.css('position');

    function positionFloater(a$Win) {
        // Set the original position to allow the browser to adjust the horizontal position
        $elementToStick.css('position', origPosition);

        // Test how far down the page is scrolled
        var scrollTop = a$Win.scrollTop();
        // If the page is scrolled passed the top of the element make it stick to the top of the screen
        if (top < scrollTop) {
            // Get the horizontal position
            var left = $elementToStick.offset().left;
            // Set the positioning as fixed to hold it's position
            $elementToStick.css('position', 'fixed');
            // Reuse the horizontal positioning
            $elementToStick.css('left', left);
            // Hold the element at the top of the screen
            $elementToStick.css('top', 0);
        }
    }

    // Perform initial positioning
    positionFloater($(window));

    // Reposition when the window resizes
    $(window).resize(function (e) {
        positionFloater($(this));
    });

    // Reposition when the window scrolls
    $(window).scroll(function (e) {
        positionFloater($(this));
    });
};

截至2017年1月和Chrome 56的发布，大多数常用的浏览器都支持CSS中的position: sticky属性。

#thing_to_stick {
  position: sticky;
  top: 0px;
}

在火狐和Chrome浏览器中都是如此。

在Safari中，你仍然需要使用position: -webkit-sticky。

Polyfills可用于Internet Explorer和Edge;https://github.com/wilddeer/stickyfill似乎是个不错的网站。

下面是一个使用jquery-visible插件的例子:http://jsfiddle.net/711p4em4/。

HTML:

<div class = "wrapper">
    <header>Header</header>
    <main>
        <nav>Stick to top</nav>
        Content
    </main>
    <footer>Footer</footer>
</div>

CSS:

* {
    margin: 0;
    padding: 0;
}

body {
    background-color: #e2e2e2;
}

.wrapper > header,
.wrapper > footer {
    font: 20px/2 Sans-Serif;
    text-align: center;
    background-color: #0040FF;
    color: #fff;
}

.wrapper > main {
    position: relative;
    height: 500px;
    background-color: #5e5e5e;
    font: 20px/500px Sans-Serif;
    color: #fff;
    text-align: center;
    padding-top: 40px;
}

.wrapper > main > nav {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    font: 20px/2 Sans-Serif;
    color: #fff;
    text-align: center;
    background-color: #FFBF00;
}

.wrapper > main > nav.fixed {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
}

JS(包括jquery-visible插件):

(function($){

    /**
     * Copyright 2012, Digital Fusion
     * Licensed under the MIT license.
     * http://teamdf.com/jquery-plugins/license/
     *
     * @author Sam Sehnert
     * @desc A small plugin that checks whether elements are within
     *       the user visible viewport of a web browser.
     *       only accounts for vertical position, not horizontal.
     */
    var $w = $(window);
    $.fn.visible = function(partial,hidden,direction){

        if (this.length < 1)
            return;

        var $t        = this.length > 1 ? this.eq(0) : this,
            t         = $t.get(0),
            vpWidth   = $w.width(),
            vpHeight  = $w.height(),
            direction = (direction) ? direction : 'both',
            clientSize = hidden === true ? t.offsetWidth * t.offsetHeight : true;

        if (typeof t.getBoundingClientRect === 'function'){

            // Use this native browser method, if available.
            var rec = t.getBoundingClientRect(),
                tViz = rec.top    >= 0 && rec.top    <  vpHeight,
                bViz = rec.bottom >  0 && rec.bottom <= vpHeight,
                lViz = rec.left   >= 0 && rec.left   <  vpWidth,
                rViz = rec.right  >  0 && rec.right  <= vpWidth,
                vVisible   = partial ? tViz || bViz : tViz && bViz,
                hVisible   = partial ? lViz || rViz : lViz && rViz;

            if(direction === 'both')
                return clientSize && vVisible && hVisible;
            else if(direction === 'vertical')
                return clientSize && vVisible;
            else if(direction === 'horizontal')
                return clientSize && hVisible;
        } else {

            var viewTop         = $w.scrollTop(),
                viewBottom      = viewTop + vpHeight,
                viewLeft        = $w.scrollLeft(),
                viewRight       = viewLeft + vpWidth,
                offset          = $t.offset(),
                _top            = offset.top,
                _bottom         = _top + $t.height(),
                _left           = offset.left,
                _right          = _left + $t.width(),
                compareTop      = partial === true ? _bottom : _top,
                compareBottom   = partial === true ? _top : _bottom,
                compareLeft     = partial === true ? _right : _left,
                compareRight    = partial === true ? _left : _right;

            if(direction === 'both')
                return !!clientSize && ((compareBottom <= viewBottom) && (compareTop >= viewTop)) && ((compareRight <= viewRight) && (compareLeft >= viewLeft));
            else if(direction === 'vertical')
                return !!clientSize && ((compareBottom <= viewBottom) && (compareTop >= viewTop));
            else if(direction === 'horizontal')
                return !!clientSize && ((compareRight <= viewRight) && (compareLeft >= viewLeft));
        }
    };

})(jQuery);

$(function() {
    $(window).scroll(function() {
        $(".wrapper > header").visible(true) ?
            $(".wrapper > main > nav").removeClass("fixed") :
            $(".wrapper > main > nav").addClass("fixed");
    });
});

你可以简单地使用css，将你的元素定位为fixed:

.fixedElement {
    background-color: #c0c0c0;
    position:fixed;
    top:0;
    width:100%;
    z-index:100;
}

编辑:你应该有一个绝对位置的元素，一旦滚动偏移到达元素，它应该被改变为固定，顶部位置应该被设置为零。

你可以用scrollTop函数检测文档的顶部滚动偏移量:

$(window).scroll(function(e){ 
  var $el = $('.fixedElement'); 
  var isPositionFixed = ($el.css('position') == 'fixed');
  if ($(this).scrollTop() > 200 && !isPositionFixed){ 
    $el.css({'position': 'fixed', 'top': '0px'}); 
  }
  if ($(this).scrollTop() < 200 && isPositionFixed){
    $el.css({'position': 'static', 'top': '0px'}); 
  } 
});

当滚动偏移量达到200时，元素会粘在浏览器窗口的顶部，因为是固定放置的。