How do I make it so that Dreamweaver CS6 doesn't give me a syntax error when I use let instead of var?
The "Edit > Preferences > Linting then Edit the JS file" is a bogus answer, there is no "linting" option in the preferences of Dreamweaver CS6. The "linting" feature wasn't added until Creative Cloud. It is unlikely that there will be a patch, Adobe wants you to switch to a subscription-based version instead.
Ok, just go to: Edit > Preferences > Linting then Edit the JS file.
add this property:
"esversion" : 6
This helped me.
来源：https://stackoverflow.com/questions/45822265/adding-javascript-es6-to-dreamweaver-cs6