Simultaneously Increment Two Variables in JavaScript

Did you know that you can update two variables at the same time in JavaScript?

In some contexts, one-liners that shorten multi-line snippets can be very useful.

Here is an example of adding a number to two variables:

numOne += 1;
numTwo += 1;

That snippet can be shortened to this one-liner, while maintaining the exact same behavior:

numOne += -numTwo + (numTwo += 1);

The caveat here is that numOne and numTwo must be incremented by the same number.

However, you can use any number, not just 1.

This one-liner can be slightly modified to work for subtraction, too:

numOne -= -numTwo + (numTwo += 1);

The above snippet will subtract 1 from both numOne and numTwo.

Conclusion

Anyway, this is just one of the many simple tricks you can use in JavaScript to shorten otherwise multi-line operations into one line.

Enjoy!