如何避免 CoffeeScript 方法变量被包装在对象文字中？
CoffeeScript 将方法内声明的变量包装在对象文字中。
所以，这样：
@Templates =
get: (templateName) ->
result: '' # DECLARED HERE
$.ajax(
'Views/Templates/' + templateName + '.html',
type: 'GET'
dataType: 'html'
success: (data) ->
result = data # ASSIGNED HERE
async: false
)
return result # RETURNED HERE
变成这样：
(function() {
this.Templates = {
get: function(templateName) {
({
result: '' //DECLARED IN AN OBJECT LITERAL - I DON'T WANT THIS
});
$.ajax('Views/Templates/' + templateName + '.html', {
type: 'GET',
dataType: 'html',
success: function(data) {
var result; //DECLARED LOCAL TO THE CALLBACK - I DON'T WANT THIS
return result = data;
},
async: false
});
return result; //RETURNED HERE - UNASSIGNED
}
};
}).call(this);
但我需要的，对我有用的是：
(function() {
this.Templates = {
get: function(templateName) {
var result = '' //DECLARED HERE
$.ajax('Views/Templates/' + templateName + '.html', {
type: 'GET',
dataType: 'html',
success: function(data) {
return result = data; //ASSIGNED HERE
},
async: false
});
return result; //RETURNED HERE
}
};
}).call(this);
我做错了什么？我该如何解决这个问题？
CoffeeScript wraps variables declared inside methods in an object literal.
So, this:
@Templates =
get: (templateName) ->
result: '' # DECLARED HERE
$.ajax(
'Views/Templates/' + templateName + '.html',
type: 'GET'
dataType: 'html'
success: (data) ->
result = data # ASSIGNED HERE
async: false
)
return result # RETURNED HERE
Becomes this:
(function() {
this.Templates = {
get: function(templateName) {
({
result: '' //DECLARED IN AN OBJECT LITERAL - I DON'T WANT THIS
});
$.ajax('Views/Templates/' + templateName + '.html', {
type: 'GET',
dataType: 'html',
success: function(data) {
var result; //DECLARED LOCAL TO THE CALLBACK - I DON'T WANT THIS
return result = data;
},
async: false
});
return result; //RETURNED HERE - UNASSIGNED
}
};
}).call(this);
But what I need, and that works for me, is this:
(function() {
this.Templates = {
get: function(templateName) {
var result = '' //DECLARED HERE
$.ajax('Views/Templates/' + templateName + '.html', {
type: 'GET',
dataType: 'html',
success: function(data) {
return result = data; //ASSIGNED HERE
},
async: false
});
return result; //RETURNED HERE
}
};
}).call(this);
What am I doing wrong? How can I fix this?
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评论（3）
你所说的闭包并不是闭包（JavaScript 中的闭包始终是函数）。它是一个括在括号中的对象文字。
我对 CoffeeScript 不太熟悉，但是如果您希望
result成为get函数中的局部变量，我相信您想要更改为
前者是对象初始值设定项格式（因此它被转换为对象文字），后者是变量赋值。似乎在 CoffeeScript 网站的词法范围下有所介绍。
What you've called a closure isn't a closure (closures in JavaScript are always functions). It's an object literal wrapped in parentheses.
I'm not really au fait with CoffeeScript, but if you want
resultto be a local variable in thegetfunction, I believe you want to changeto
The former is the object initializer format (hence it getting translated into an object literal), the latter is a variable assignment. Seems to be covered on the CoffeeScript site under lexical scoping.
通过
result: ''您可以声明对象的属性。您需要的是通过result = ''声明一个局部变量：By
result: ''you declare a property of an object. What you needed was to declare a local variable byresult = '':为什么要使用
:？它没有被包装在闭包中，您只是定义了一个匿名对象表达式。只需这样做：
也就是说，为什么要执行同步 GET？这是非常不受欢迎的，并且会使您的网站响应速度降低。
Why are you using a
:? It's not being wrapped in a closure, you are just defining an anonymous object expression.Just do this:
That said, why are you doing a synchronous GET? That's very frowned upon and will make your site must less responsive.