Are there constants in JavaScript?

Is there a way to use constants in JavaScript?

If not, what's the common practice for specifying variables that are used as constants?

Since ES2015, JavaScript has a notion of const:

const MY_CONSTANT = "some-value";

This will work in pretty much all browsers except IE 8, 9 and 10. Some may also need strict mode enabled.

You can use var with conventions like ALL_CAPS to show that certain values should not be modified if you need to support older browsers or are working with legacy code:

var MY_CONSTANT = "some-value";

Stack Overflow Q#130396, score: 1037