一个简单的jQuery插件制作学习过程及实例

(function ($) {
//code in here
})(jQuery);

$.fn.dBox = function (options) {
var defaults = {
//各种属性及其默认值
};
var opts = $.extend(defaults, options);
//function codes in here
};

$.fn.dBox = function (options) {
var defaults = {
opacity: 0.6, //for mask layer
drag: true,
title: 'dBox',
content: '',
left: 400,
top: 200,
width: 600,
height: 300,
setPos: false, //if use the customer's left and top
overlay: true, //if use the mask layer
loadStr: 'Loading',
ajaxSrc: '',
iframeSrc: ''
};
var opts = $.extend(defaults, options);
//function codes in here
};

//build html code of the dBox
var dBoxHtml = "";
var dBoxBG = "";
var loading = "";

//click event
$(this).click(function () {
$("body").append(dBoxHtml);
//case ajax
if (opts.ajaxSrc != "") {
$("#d_content").append("");
$("#d_ajaxcontent").load(opts.ajaxSrc);
}
//case iframe
else if (opts.iframeSrc != "") {
$("#d_content").append("");
}
addCSS();
//case drag
if (opts.drag == true) {
drag();
}
$("#d_close").click(dBoxRemove);
return false;
});

//add css to the dBox
function addCSS() {
var pos = setPosition();
$("#dBox").css({ "left": pos[0], "top": pos[1], "width": opts.width + "px", "height": opts.height + "px" });
if (opts.overlay) {
var wh = getPageSize();
$(dBoxBG).appendTo("body").css({ "opacity": opts.opacity, "width": wh[0], "height": wh[1] });
}
}

//calc the size of the page to put the mask layer cover the whole document
function getPageSize() {
if ($(window).height() > $(document).height()) {
h = $(window).height();
} else {
h = $(document).height();
}
w = $(window).width();
return Array(w, h);
}
//calc the position of the dBox to put the dBox in the center of current window
function setPosition() {
if (opts.setPos) {
l = opts.left;
t = opts.top;
} else {
var w = opts.width;
var h = opts.height;
var width = $(document).width();
var height = $(window).height();
var left = $(document).scrollLeft();
var top = $(document).scrollTop();
var t = top + (height / 2) - (h / 2);
var l = left + (width / 2) - (w / 2);
}
return Array(l, t);
}

//drag the dBox
//this event contains four events(handle.mousedown,move,out,up)
function drag() {
var dx, dy, moveout;
var handle = $("#dBox").find("#d_head>#d_title").css('cursor', 'move');
handle.mousedown(function (e) {
//cal the distance between e and dBox
dx = e.clientX - parseInt($("#dBox").css("left"));
dy = e.clientY - parseInt($("#dBox").css("top"));
//bind mousemove event and mouseout event to the dBox
$("#dBox").mousemove(move).mouseout(out).css({ "opacity": opts.opacity });
handle.mouseup(up);
});
move = function (e) {
moveout = false;
win = $(window);
var x, y;
if (e.clientX - dx <0) {
x = 0;
} else {
if (e.clientX - dx > (win.width() - $("#dBox").width())) {
x = win.width() - $("#dBox").width();
} else {
x = e.clientX - dx;
}
}
if (e.clientY - dy <0) {
y = 0;
} else {
y = e.clientY - dy;
}
$("#dBox").css({
left: x,
top: y
});
}
out = function (e) {
moveout = true;
setTimeout(function () {
moveout && up(e);
}, 10);
}
up = function (e) {
$("#dBox").unbind("mousemove", move).unbind("mouseout", out).css("opacity", 1);
handle.unbind("mouseup", up);
}
}

//close the dBox
function dBoxRemove() {
if ($("#dBox")) {
$("#dBox").stop().fadeOut(200, function () {
$("#dBox").remove();
if (opts.overlay) {
$("#d_bg").remove();
$("#d_iframebg").remove();
}
});
}
}