2019
https://www.jsmonday.dev/articles/17/let-is-the-new-var
    https://habr.com/ru/post/466559/
https://tylermcginnis.com/var-let-const/
2018
https://jamie.build/const
    https://medium.com/webbdev/vs-b15bc3155c63
https://andy-carter.com/blog/variable-scope-in-modern-javascript
https://alistapart.com/article/fixing-variable-scope-issues-with-ecmascript-6
    https://habr.com/company/ruvds/blog/420359/
https://medium.freecodecamp.org/javascripts-var-let-and-const-variables-explained-with-a-story-2038e3c6b2f9
https://alistapart.com/article/fixing-variable-scope-issues-with-ecmascript-6
    https://medium.com/webbdev/var-let-%D0%B8%D0%BB%D0%B8-const-%D0%BF%D1%80%D0%BE%D0%B1%D0%BB%D0%B5%D0%BC%D1%8B-%D0%BE%D0%B1%D0%BB%D0%B0%D1%81%D1%82%D0%B5%D0%B9-%D0%B2%D0%B8%D0%B4%D0%B8%D0%BC%D0%BE%D1%81%D1%82%D0%B8-%D0%BF%D0%B5%D1%80%D0%B5%D0%BC%D0%B5%D0%BD%D0%BD%D1%8B%D1%85-d5c2e04bf467