Date.parse() returns null instead of NaN

[jpettitt]

After installing datejs Date.parse() returns null instead of NaN

This breaks compatibility with the stock Date() object which in turn breaks the conditional request logic in express.static causing spurious HTTP 412 responses.

Gross hack work around

require('datejs');

module.exports = function fixdate() {
  Date._datejs_parse = Date.parse;
  Date.parse = function parse(str) {
    return this._datejs_parse(str) || NaN;
  };
};

[abritinthebay]

Ah, interesting quirk.
Good find.

[dougwilson]

The spec for Date.parse is https://www.ecma-international.org/ecma-262/5.1/#sec-15.9.4.2

Unrecognisable Strings or dates containing illegal element values in the format String shall cause Date.parse to return NaN.

[dougwilson]

The native Date.parse is also required to return a plain Number, but this overrides the global Date.parse to return an object instead.

[dougwilson]

@jpettitt if I'm following the issue #198 correctly, you cannot use datejs with Express until v2 of datejs.

[dougwilson]

FWIW, the biggest issue with the difference is that it's not even safe to perform basic inequality operations on the result of Date.parse like you can do natively.

For example, given Date.parse('foo') < Date.parse('2017-01-01T00:00:00Z'), without datejs loaded, that returns false, but when it's loaded, even though it still fails to parse the "foo" string, it now returns true.

[abritinthebay]

Indeed. We're never going to be 100% compatible with the Native parse (ie - being a number) because... well.. that's the point of this library (to extend the native Date object).

However this (returning NaN) seems like a good general compatibility change. Quite reasonable.

Would require a SemVer Major though, potentially, as it's a breaking backwards compatible change.

PRs welcome - as I'm snowed under with "real" work so OSS I'm afraid is low priority.