Add fromNow

[moeriki]

This is a very common pattern in my code. Not sure about how other people use it.

Date.now() + ms('2h')

I'd love to add fromNow as shortcut.

const inTwoHours = ms.fromNow('2h'); // 1508165682168 ;)

Yay or nay?

[mikemfleming]

I like the idea of that. I'll take a crack at it now.

Wouldn't want to mess with existing implementations that rely on exporting a function instead of an ms object with methods, though.

Maybe the call would look something more like ms('2h', { from: Date.now() });?

module.exports = function(val, options) {
  options = options || {};
  var type = typeof val;
  if (type === 'string' && val.length > 0) {
    return parse(val);
  } else if (type === 'number' && isNaN(val) === false) {
    return options.long ? fmtLong(val) : fmtShort(val);
  }
  throw new Error(
    'val is not a non-empty string or a valid number. val=' +
      JSON.stringify(val)
  );
};

[yoavmmn]

+1 on the idea. And I totally agree with @mikemfleming, a from option will be easier and faster to implement.
I hope to sit and work on a Proof Of Concept in the next day or two.

[moeriki]

{ from: … } is great as it allows users to get milliseconds relative to any date, not just now. 👍

[yoavmmn]

I think I'm done. I'll write some tests and open a PR later today.

[yoavmmn]

Opened PR #101, please review and let me know what you think.

[mikemfleming]

Awesome! I just checked it out locally with just the 2h example from above and it worked perfectly. Nice.

[jeteon]

I'm having trouble seeing the gain in going from:

Date.now() + ms('2h')

to:

ms('2h', { from: Date.now() })

What about making the above equivalent to this instead?:

ms('+2h')

[yoavmmn]

@jeteon you gain readability. ms('2h', { from: Date.now() }); is more readable and understandable than Date.now() + ms('2h'); for begginers and newcomers.
The problem with ms('+2h'); is that it'll return only the time from Date.now();. using from option allows to get the time from any Date given.

[TooTallNate]

But isn't Date.now() + ms('2h') nice and explicit already? Reads as "right now plus 2 hours". I'm not sure if an additional helper is necessary in this case.

[yoavmmn]

@TooTallNate take a look at my PR. I think we all agree that a { from: ... } option is great for this and other use-cases.

[jeteon]

What are the other use cases?

[moeriki]

In retrospect I agree the gain is rather small. I don't think this is a good idea anymore. I might make a ms wrapper package should I still be in need of something alike.

[jeteon]

I guess having a utility function like this would fix your use case?

function msAfter(duration) {
   return Date.now() + ms(duration);
}

[TooTallNate]

We're going to pass on this feature request for now. Using idiomatic JavaScript (that is, + and - operators) is more explicit and readable, especially to somebody who is not already familiar with the semantics of this ms module.