我为网站开发了某种Jcrop初始化,我设法创建了自己的命名空间.我的问题是关于这个关键字.每次我必须在任何回调函数中访问我的基础对象“aps”时,我必须将它包装在一个变量中(我选择了这个单词).有没有更好的方法呢？例如,我可以使用call或apply方法吗？这只是一个命名空间,所以我可以使用简单的aps.methodName但是为了这个例子,请不要介意.这是我的源代码：
var aps;
$(function(){
aps = function(){
// private
// variables
var bgColor = '#f5f5f5';
var threshold = 370;
var threshold_width = 800;
return {
tmpl : $('#jcrop-template').html(),upl_cont : {},form : {},logo_img : new Image(),jcrop_api : null,scaled_logo_url : '',image_filename : '',original_image_filename : '',mime : '',trueSize : '',jcrop_init : function (oiFrameRes){
$('#logo_upload_form').find('img').hide();
this.scaled_logo_url = oiFrameRes.image_url;
this.logo_url = oiFrameRes.original_image_url;
this.original_image_filename = oiFrameRes.original_image_filename;
this.image_filename = oiFrameRes.image_filename;
this.mime = oiFrameRes.mime;
this.upl_cont = $('#faceBox div#upload-container-d');
this.logo_img = new Image();
this.logo_img.that = this;
this.logo_img.name = 'logo';
this.logo_img.onload = function(){
this.true_width=this.width;
this.true_height=this.height;
this.that.resize_image();
this.that.resize_faceBox();
this.that.display_image();
}
this.logo_img.src = this.logo_url;
},resize_image : function(){
this.trueSize = '';
if(typeof (this.oSettings.trueSize)!=='undefined') delete(this.oSettings.trueSize);
if (this.logo_img.width > threshold){
if (this.logo_img.width > threshold_width){
this.trueSize = [ this.logo_img.width,this.logo_img.height ];
this.logo_img.height = this.logo_img.height / (this.logo_img.width / threshold_width);
this.logo_img.width = threshold_width;
}
}
},resize_faceBox : function(){
var width = (this.logo_img.width > threshold) ? this.logo_img.width : threshold ;
$('#faceBox').css({
left : $(window).width() / 2 - width / 2
}).
find('div.change-size').css({'width': width+30});
},display_image : function (){
if (this.jcrop_api === null) {
$logo_img = $(this.logo_img).css({'display':'block','margin-left':'auto','margin-right':'auto'})
if (this.upl_cont.find('#logo-container-d>img').length > 0){
if (this.upl_cont.find('#logo-container-d>img').attr('src').length > 0){
this.upl_cont.find('#logo-container-d').empty().append($logo_img);
}
}
else {
this.upl_cont.append(this.tmpl).find('#logo-container-d').append($logo_img);
}
var that = this;
if (typeof (this.upl_cont.find('#jcrop-menu1 a').data('events')) === 'undefined'){
this.upl_cont.find('#jcrop-menu1 a').click(function(){
if (this.href.indexOf('#crop')>-1){
$(this).closest('div').hide();
that.upl_cont.find('#jcrop-menu2').show();
that.setup_crop();
}
if (this.href.indexOf('#close')>-1){
manageIframeResponse();
}
location.hash = '';
return false;
});
}
}
else {
this.reset();
}
},reset : function(){
$('#jcrop-menu2',this.upl_cont).find('a').unbind('click').end().hide();
$('#jcrop-coords-f',this.upl_cont).find('input[type="text"]').each(function(){this.value="";}).end().hide();
$('#jcrop-menu1',this.upl_cont).find('a').unbind('click').end().show();
this.jcrop_api.destroy();
this.jcrop_api=null;
this.display_image();
},send_form : function (){
var sPost = $(this.form).find('input[name="image_filename"]').val(this.image_filename).end()
.find('input[name="original_image_filename"]').val(this.original_image_filename).end()
.find('input[name="mime"]').val(this.mime).end()
.find('input[name="user_url"]').val($('#logo_upload_base_url').val()).end()
.find('input[name="user_key"]').val($('#logo_upload_user_key').val()).end()
.serialize();
$.ajax({
url:'iframe_upload.PHP',type:'POST',data: sPost,success : function(response){
manageIframeResponse();
},dataType : 'json'
});
},setup_crop : function (){
var that = this;
if (this.jcrop_api === null) {
this.form = this.upl_cont.find('form#jcrop-coords-f').get(0);
this.upl_cont.find('#jcrop-menu2>a').click(function(){ that.send_form();return false; });
this.updateForm = function (){
var c = arguments[0];
that.form.x1.value=c.x;
that.form.x2.value=c.x2;
that.form.y1.value=c.y;
that.form.y2.value=c.y2;
that.form.h.value=c.h;
that.form.w.value=c.w;
}
this.oSettings.onSelect = this.updateForm;
if (typeof (this.trueSize) !== 'string' && $.isArray(this.trueSize)){
$.extend(this.oSettings,{'trueSize':this.trueSize});
}
$('#faceBox #logo-container-d>img').Jcrop( this.oSettings,function(){
that.jcrop_api = this;
var _x1 = (that.logo_img.true_width*0.1).toFixed();
var _y1 = (that.logo_img.true_height*0.1).toFixed();
var _x2 = (that.logo_img.true_width*0.9).toFixed();
var _y2 = (that.logo_img.true_height*0.9).toFixed();
that.jcrop_api.setSelect([0,that.logo_img.true_width,that.logo_img.true_height]);
that.jcrop_api.animateto([_x1,_y1,_x2,_y2]);
});
}
},updateForm : function (){},oSettings : {
onSelect:'',onChange:'',keySupport: false,bgColor:bgColor,aspectRatio:1,minSize:[0,0]
}
}
}();
$(document).bind('afterClose.faceBox',function() {
if (aps.jcrop_api !=null) {
aps.jcrop_api.destroy();
aps.jcrop_api=null;
}
});
});
解决方法
无论何时使用函数调用*调用函数,此值都将设置为全局变量(或在严格模式下未定义) – 即使从方法调用函数也是如此.道格拉斯·克罗克福德实际上已将此描述为该语言的一个缺陷.
将此值保存到函数可以访问的变量中是处理此问题的标准方法.
如果您真的想控制回调中的内容,可以使用apply或call.两者都将您想要设置的第一个参数作为第一个参数.不同之处在于apply期望所有函数的参数作为数组传递,而call期望您单独列出它们.
因此,如果在你的ajax回调中,你想调用manageIframeResponse,请传递ajax调用的响应(我知道你的例子没有传递响应,我只是说明你将如何做),并将其值设为与当前对象相同,您可以这样做：
var self = this;
$.ajax({
success : function(response){
manageIframeResponse.apply(self,[response]); //<--- apply wants your arguments in array form
}
});
或者,由于您的参数尚未采用数组形式,因此您可以更简单地使用调用
var self = this;
$.ajax({
success : function(response){
manageIframeResponse.call(self,response); //<---call takes the arguments listed out one at a time
}
});
*
有不同的方法来调用函数.
函数调用意味着您只是调用恰好位于当前范围内的函数：
foo() //inside foo,this will be the global object (or undefined in strict mode)
方法调用意味着您正在调用附加到对象的函数
myObj.foo() //inside foo,this will be myObj
这里有一个例子,如果你不小心,这会让你感到沮丧.
function objCreator() {
var y = "There";
function privateFunc() {
alert(y); //alerts There as expected
alert(this.someField); //undefined: whoops - this is the global object,} //so there's no someField
return {
x: "Hi",someField: "blah",foo: function () {
alert(this.x);
privateFunc();
}
};
}