[js-experimental] Add the ability to parse the '::' operator in Semgrep for javascript

[Jason-Lim00]

Is your feature request related to a problem? Please describe:

Semgrep currently does not support parsing for the '::' operation in javascript. An example can be found in the following error and code snippet below in the additional context.

Describe the solution you'd like:

It would be nice to add the ability to parse this to help with faster code writing as well as keeping up with shorthand ways of coding a certain operation.

Describe alternatives you've considered:

The only alternative is to revert back to using the bind() operation which is the longhand for that '::' operator.

Additional context:

Error:

| Semgrep exited with 629 errors:
|    Semgrep Core WARN - Syntax error: When running typescript.react.security.audit.react-html-element-spreading.react-html-element-spreading on js/component/Input/PowerDropdown.js: `::` was unexpected

Code snippet that it is faulty on:

handleEscapePress = ::this.handleEscapePress;
handleDocumentClick = ::this.handleDocumentClick;

[mjambon]

I can't find documentation for this. It looks like it was a proposal for ES7 (2016) but there's no trace of it in the ES7 spec or later. Here's confirmation that the bind operator :: wasn't adopted in javascript. It wasn't adopted in typescript either but a comment indicates that the ES proposal has been recently revived (Sep 2021).

We can support whatever is supported by typescript via the tree-sitter-typescript implementation but if it's not an official feature of typescript, it's going to be complicated.