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JavaScript

Posted by Danny Martin
Danny Martin
10,912 Points

Shouldn't the variables be declared using 'const' or 'let' instead of 'var' to comply with ES6 standards?

It seems that this lesson was created after the ES6 release, yet still exclusively declares variables using 'var'...

andren
andren
28,558 Points

You have not linked to the lesson in question so I can't really comment on your question either way, but it should be noted that many tracks do contain courses that was recorded before Treehouse transitioned to ES6 but comes after the ES6 courses in the track.

Danny Martin
Danny Martin
10,912 Points

My bad, first time posting a question and I didn't realize that the lesson wasn't linked by default. The lessons I am referring to are the jQuery Basics "Creating a Simple Lightbox" videos.

1 Answer

Eric Butler
Eric Butler
33,512 Points

Daniel, I understand your confusion because Treehouse has done a terrible job explaining this, so allow me: ES6 (aka ES2015) was indeed "released" in June 2015, but even today in March 2017, there are plenty of very-much-used internet browsers -- desktop and mobile -- that do not support ES6 natively, so if you use let and const instead of var without any compiler (like Babel JS), you risk all of your site's JavaScript being completely broken for users. Check browser support for "let" on caniuse.com and click the "Show All" button to see all the browser versions (in particular iOS Safari up to 9.3, macOS Safari up to 9.1, Internet Explorer up to 10) for which let will be completely meaningless.

While we are close to being able to switch to ES6 syntax, it's pretty foolish to do so without "compiling" your JavaScript (basically a fancy way of saying using an automated process to convert ES6 syntax back into "old" JavaScript syntax) before you put it in a production environment. Let me know if you have any questions.