js: functional and modern syntax

[mio-19]

generate more elegant code

it get rid of

function(...){
return function(...){
return function(...){
return function(...){
...

[LingDong-]

Looking great, let me know if it's ready for merging, thanks!

[mio-19]

it's ready for merging

[LingDong-]

Thanks!

I see you did a x=>y=>z=>{} to get rid of funcurlvls, pretty neat.

I'm thinking if functions should still be initialized to ()=>0. All other types initialize to a value. Numbers to 0, Bools to false, Objects to {}. I know user shouldn't need to use a function before it is defined, but let's not make assumptions. This also makes runtime typechecking more consistent.

One thing that is debatable is that maybe we can return _=>_ the identity function instead. I guess either is quite reasonable.

What do you think?

[mio-19]

I think _=>{} is more reasonable

[LingDong-]

Thanks a lot!

[mio-19]

@LingDong- Screenshots and CHANGELOG need to be updated