CS2 Discussion: Features: Allow backticks to be used inside embedded Javascript blocks

[greghuc]

As discussed here, I'm splitting out a separate issue for allowing backticks to be used inside embedded Javascript blocks.

This is a straight-up bug fix for an issue that has been around since 2011, but has become more important since the introduction of ES6 template literals.

ES6 template literals cannot be used in an embedded Javascript block, since the new syntax uses backticks. Backticks are already used by Coffeescript to define the start and end of the JS block. This example blows up:

`3 + 2 = ${3 + 2}`

The proposed fix is for Coffeescript to allow embedded Javascript blocks to be delineated with 3-backticks markdown-style, and not escape backticks in the Javascript block. E.g.:

    ```
    `3 + 2 = ${3 + 2}`
    ```

Reasoning:

• Was the solution commonly proposed in the Coffeescript issue first raised about backticks in 2011.
• Matches the Markdown code syntax.
• Echos the Coffeescript block-string syntax, which uses three double-quotes

[GeoffreyBooth]

Released in CoffeeScript 1.12.0.

[coffeescriptbot]

Migrated to jashkenas/coffeescript#4938