按名称调用函数

Sometimes we need to call a function by its name. I can do it in plain JavaScript as below:

有时我们需要通过名称来调用函数。我可以用普通的JavaScript做到,如下所示:

global=this
function add(a,b){return a+b}
global['add'](1,2)

Which works as expected and add() gets called.

哪个工作正常,add()被调用。

Equivalent CoffeeScript code might can be written as below.

等效的CoffeeScript代码可以编写如下。

global=@
add=(a,b)->a+b
global['add'](1,2)

which compiles to JavaScript as:

编译为JavaScript的:

(function() {
  var add, global;
  global = this;
  add = function(a, b) {
    return a + b;
  };
  global['add'](1, 2);
}).call(this);

...and it doesn't work.

......它不起作用。

Microsoft JScript runtime error: Object doesn't support this property or method

Is there an easy solution to this problem?

这个问题有一个简单的解决方案吗?

Note:

1. I am not running the code in a browser therefore there is no window object. But in plain JS I can always capture the global scope by assigning global=this and then get the function pointer from it.

   我没有在浏览器中运行代码,因此没有窗口对象。但是在简单的JS中,我总是可以通过赋值global = this捕获全局范围,然后从中获取函数指针。

2. One solution in CoffeeScript I found is by declaring all functions as member of a global object like global.add=[function definition]. But then I have to normally call the function as global.add(). And it's more boiler plate than necessary.

   我发现CoffeeScript中的一个解决方案是将所有函数声明为全局对象的成员,如global.add = [function definition]。但是我必须通常将该函数称为global.add()。它比锅炉板更多。

Is there a simple hack? Or any simpler solution?

有一个简单的黑客?或者更简单的解决方案?

2 个解决方案

#1

Your add is a local variable. Use

你的add是一个局部变量。使用

@add=(a,b)->a+b

to attach it to the global object. Since global is the global scope of your script you can still call add without prefixing it with global..

将它附加到全局对象。由于global是脚本的全局范围,因此您仍然可以调用add而不使用global作为前缀。

#2

By default the CoffeeScript compiler wraps every file in a closure scope, but you can disable this behavior by adding the --bare switch as compiler option.

默认情况下,CoffeeScript编译器会封装闭包范围中的每个文件,但您可以通过将--bare开关添加为编译器选项来禁用此行为。

add.coffee:

add = (a,b) -> a+b

When you run: coffee --compile add.coffee

当你运行:coffee --compile add.coffee

That will produce:

这会产生:

(function() {
  var add;
  add = function(a,b) {
    return a+b;
  };
}).call(this);

Now try run it with the --bare switch coffee --bare --compile add.coffee

现在尝试使用--bare switch coffee --bare --compile add.coffee运行它

That will produce:

这会产生:

var add;
add = function(a, b) {
  return a + b;
};

Now you file is not closure scoped, and you can do it the way you did it before.

现在你的文件不是封闭范围,你可以像以前那样做。