Add bemhtml-es2015 tech

[rakchaev]

No description provided.

[miripiruni]

Why we need such techs (es2015, es2016, etc) in enb-bemxjst?

[miripiruni]

Unused variable.

[rakchaev]

In techs such enb-es2015 (https://github.com/DimitryDushkin/enb-es2015) we can transpile just source files (form blocks) before gathering to a single file.
It's faster then transpile a big file.

If we need to transpile bemhtml code for browser, we should use babel+bemhtml processing before gathering to a single file.
It seems this is appropriate place: https://github.com/enb/enb-bemxjst/blob/master/techs/bemhtml.js#L67-L68

[qfox]

@miripiruni Because of ENB-mechanics. It doesn't allow to process source files before putting them to processing technologies.

[tadatuta]

@rakchaev it should be possible to compile BEMHTML bundle with default tech, transpile it to ES5 with universal transpiler tech and then merge with client bundle.

[qfox]

it should be possible to compile BEMHTML bundle with default tech

But he said:

It's (transpiling few small files) faster than transpile a big file.

[tadatuta]

I've got two questions:

1. Why not to transpile just in production mode when build time is not so important?
2. Is client template bundle really so huge that build time difference become important?

[rakchaev]

@tadatuta

1. It's possible. But if your browser doesn't support for some ES feature or you need to debug site in not modern browser, code won't work.
2. It depends on project. It can be big. But difference between transpiling of n chunks of m size and 1 chunk of n*m size is really significant. Likely, it's because of parsing to AST or manipulation of AST logic.