/*
* 功能: 创建一个可以让页面滚动到顶部的按钮, 常见于各种社交网站的微博列表.
* 备注: DOM被设置成了浮动的, 用户可以自己设定位置, 传入right, bottom参数即可
还可以配置滚到条到多高的时候会显示插件图标.
*/
(function ($) {
$.fn.scrolltop = function (options) {
var opts = $.extend({}, $.fn.scrolltop.defaults, options);
var run2top = function () {
var scrollDist = $(window).scrollTop();
if (scrollDist > 0) {
scrollDist -= opts.topSpeed;
scrollDist = Math.max(scrollDist, 0);
$(window).scrollTop(scrollDist);
setTimeout(run2top, 1);
}
};
return this.each(function () {
var $this = $(this);
$this.css("opacity", "0.3");
$this.css("background", "url('u=4251301862,936291425&fm=214&gp=0.jpg') no-repeat");
$this.css("width", opts.width);
$this.css("height", opts.height);
$this.css("position", "fixed");
$this.css("right", opts.right);
$this.css("bottom", opts.bottom);
$this.hover(
function () {
$(this).css('opacity', '1.0');
},
function () {
$(this).css('opacity', '0.5');
}
);
$this.click(function () {
//$(window).scrollTop(0);
run2top();
});
$(window).scroll(function () {
var scrollDist = $(window).scrollTop();
if (scrollDist >= opts.heightThreshhold) { //当滚动条离顶部超过阈值的时候, 就显示
$this.css("display", "block");
} else {
$this.css("display", "none");
}
});
});
};
$.fn.scrolltop.defaults = {
heightThreshhold: 1000,
width: "50px",
height: "50px",
right: "8%",
bottom: "30px",
topSpeed: 50
};
})(jQuery);
