context.call: does not support non-global function names

When calling a function, only global function names are supported. Functions which are properties of an object, or otherwise nested/scoped, are not supported: e.g. object.fn.

This works:

context = MiniRacer::Context.new
context.eval('bare = () => 1')
# => #<MiniRacer::JavaScriptFunction:0x00007f96e8acf798>
context.call('bare')
# => 1

This breaks:

context = MiniRacer::Context.new
context.eval('object = {}')
context.eval('object.nested = () => 1')
# => #<MiniRacer::JavaScriptFunction:0x00007f96e899d5a0>
context.call('object.nested')
# => Unknown JavaScript method invoked (MiniRacer::RuntimeError)

Environment:

• ruby: 3.0.2
• mini_racer: 0.5.0

[tisba]

That’s a good point, @gi, thx!

For reference https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const:

Constants are block-scoped, much like variables declared using the let keyword.[…]

But what surprises me then is that the defined constant is still visible on subsequent invocations:

require "mini_racer"

ctx = MiniRacer::Context.new
ctx.eval("const foo = 42;")
a = ctx.eval("foo + 1;")
# a => 43
ctx.eval("foo = 42;")

# JavaScript at <anonymous>:1:5: TypeError: Assignment to constant variable. (MiniRacer::RuntimeError)

Since I can also use foo in subsequent #eval calls, it looks like the same scope is used every time. I think these issues are related after all and it feels like a similar lookup issue 🤔

[gi]

The original issue here is that the string used to identify the function to call is not evaluated to lookup the function:

In Ruby,

context.call("a.b")

is interpreted in JavaScript as

this["a.b"]()

instead of

this["a"]["b"]()