Calling a function by its name

Question

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

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

Which works as expected and add() gets called.

Equivalent CoffeeScript code might can be written as below.

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

which compiles to JavaScript as:

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

...and it doesn't work.

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

Is there an easy solution to this problem?

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.

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.

Is there a simple hack? Or any simpler solution?

Answer 1

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.

add.coffee:

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

When you run: coffee --compile add.coffee

That will produce:

(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

That will produce:

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.

Answer 2

Your add is a local variable. Use

@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..