Using NPM `redis` package, .exists(...) always returns true. Why?

Question

I have a little Node.js project with Redis that is in development. What I am currently seeing is that client.exists(anything) returns true, even when that key does not exist in the Redis store. Here is some code to demonstrate what I am doing.

const key = 'k'
const content = 'blah blah'
client.rpush(key, content)

I run the above code and I stop. Now, on the command line, I do the following:

> redis-cli
:6379> exists k
true
:6379> exists foo
false

Awesome! As expected. Now, I run the following code back in Node.js:

const key = 'k'
if(client.exists(key)) console.log('should print')
if(client.exists('foo')) console.log('should not print')

Unfortunately, the result I'm getting in console output is:

should print
should not print

Why is Redis in Node.js reporting that something exists when Redis on the CLI reports, as expected, that thing does not exist?

Answer 1

Because you're using the library wrong, as it's asynchronous.

If you read the docs, you'll find that you need to pass in a result callback (or promisify the library to use promises instead).

client.exists(key, (err, ok) => {
  if (err) throw err;
  console.log(ok);
});