Show HN: NodeScript- JavaScript Without the Variable Declarations and Semicolons

https://github.com/nodescript/nodescript

by pretodor • 9 years ago

5 7 9 years ago

rco8786• 9 years ago

Interesting. It's worth noting that semicolons are generally optional in javascript, and there's a growing contingency of folks who actively do not use them and rely on their build tools to inject where necessary. Sounds like it would lead to subtle bugs but I guess it works ok.

Anyway, nice work in general! Assuming this only works with 'let' to avoid the weirdness around 'var' scoping?

pretodor3• 9 years ago

Regarding the semicolons, due to the insertion mechanism JavaScript uses, lines starting with '[', '(', or '`' will get merged with the previous statement. So the example in the repo will get parsed in JavaScript as:

    x = 10;
    y = 20[x, y] = [y, x];

Your assumption is correct. NodeScript defaults to let-declarations. This leaves you with a block-scoped language and prevents leakage of global variables. If you want to make a global variable, you will have to explicitly write it as a property of the global object.

Thanks for the kind words. I really appreciate it.

sucrose• 9 years ago

Regarding semicolons, here's an interesting previous discussion: https://news.ycombinator.com/item?id=3842713

krapp• 9 years ago

Sounds like it would lead to subtle bugs but I guess it works ok.

It does lead to subtle bugs. The same kind of people who leave semicolons out of javascript write C but leave out the braces in statements wherever it's allowed - which also leads to subtle bugs.

I guess looking pretty and saving a couple of keystrokes is preferable to being explicit and not having to just trust that the compiler/browser/whatever is able to intuit what you want the code to be as opposed to what you wrote.

pretodor3• 9 years ago

It does lead to subtle bugs.

Have you encountered any bugs so far while testing NodeScript out? I thought I have taken care of all the gotchas when it comes to semicolons.

clusmore• 9 years ago

How does this handle shadowing? Consider, for example,

  let x = 1;
  function foo() { let x = 2; }
  function bar() { x = 3; }
  console.log(x); // 1
  foo();
  console.log(x); // 1
  bar();
  console.log(x); // 3

Without the declaration, how can you tell whether I intend to shadow or not?

Edit: I note from another comment that you state

If you want to make a global variable, you will have to explicitly write it as a property of the global object.

The example above could appear in any scope, not only the global scope. Python now has a `nonlocal` keyword (as well as the `global` keyword) to disambiguate these cases.

pretodor3• 9 years ago

The default behaviour is not to shadow variables. If you want to shadow a variable, you have to do so explicitly with the 'let' keyword.

Here is a NodeScript snippet and its equivalent in Python:

    // NodeScript
    
    x = 10
    function outer() {
        y = 20
    
        function inner() {
            x = 100
            y = 200
        }
    
        inner()
        console.log(x, y)
    }
    
    outer()


    # Python
    
    x = 10
    def outer():
        y = 20
    
        def inner():
            global x
            nonlocal y
    
            x = 100
            y = 200
    
        inner()
        print(x, y)
    
    outer()

Show HN: NodeScript- JavaScript Without the Variable Declarations and Semicolons

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