尝试使用 Opal/JQuery。我的 app.rb 文件如下所示：
require 'opal'
require 'opal-jquery'
class HTMLObject
def initialize
end
def write_to_body
end
end
class HTMLParagraph < HTMLObject
attr_accessor :inner_html
def initialize(text)
@inner_html= text
end
def write_to_body
@body = Element.find("#body")
@body.append(Element("<p>#{@inner_html}"))
end
end
p = HTMLParagraph.new("hello world")
p.write_to_body
我使用站点中的示例将其编译为 app.js。我在我的网络浏览器中使用 index.html 运行它：
<!DOCTYPE html>
<html>
<head>
<script src="jquery-1.10.1.min.js" type="text/javascript"></script>
<script src="opal.js" type="text/javascript"></script>
<script src="opal-jquery.min.js" type="text/javascript"></script>
<script src="opal-parser.js" type="text/javascript"></script>
<script src="app.js" type="text/javascript"></script>
<title></title>
</head>
<body>
</body>
</html>
当我打开页面时，我什么也看不到。控制台显示此错误跟踪：
Uncaught NameError: uninitialized constant Object::Element opal.js:1531
def.$backtrace.backtrace opal.js:1531
def.$raise opal.js:1279
def.$const_missing opal.js:575
Opal.cm opal.js:255
def.$write_to_body app.js:44
(anonymous function) app.js:51
(anonymous function)
JS 输出文件的内容如下：
function(__opal) {
var p = nil, _a, _b, self = __opal.top, __scope = __opal, nil = __opal.nil, $mm = __opal.mm, __breaker = __opal.breaker, __slice = __opal.slice, __klass = __opal.klass;
(function(__base, __super){
function HTMLObject() {};
HTMLObject = __klass(__base, __super, "HTMLObject", HTMLObject);
var def = HTMLObject.prototype, __scope = HTMLObject._scope;
def.$initialize = function() {
return nil;
};
def.$write_to_body = function() {
return nil;
};
return nil;
})(self, null);
(function(__base, __super){
function HTMLParagraph() {};
HTMLParagraph = __klass(__base, __super, "HTMLParagraph", HTMLParagraph);
var def = HTMLParagraph.prototype, __scope = HTMLParagraph._scope;
def.inner_html = def.body = nil;
def.$inner_html = function() {
return this.inner_html
},
def['$inner_html='] = function(val) {
return this.inner_html = val
}, nil;
def.$initialize = function(text) {
return this.inner_html = text;
};
def.$write_to_body = function() {
var _a, _b, _c;
this.body = ((_a = ((_b = __scope.Element) == null ? __opal.cm("Element") : _b)).$find || $mm('find')).call(_a, "#body");
return ((_b = this.body).$append || $mm('append')).call(_b, ((_c = this).$Element || $mm('Element')).call(_c, "<p>" + (this.inner_html)));
};
return nil;
})(self, ((_a = __scope.HTMLObject) == null ? __opal.cm("HTMLObject") : _a));
p = ((_a = ((_b = __scope.HTMLParagraph) == null ? __opal.cm("HTMLParagraph") : _b)).$new || $mm('new')).call(_a, "hello world");
return ((_b = p).$write_to_body || $mm('write_to_body')).call(_b);
})(Opal);
有任何想法吗？