toJSON throw exception instead of returns null

[guillaumebriday]

Describe the bug
There is a different behaviour between moment and dayjs when date is invalid and toJSON is called.

dayjs('wtf').toJSON()
> Uncaught RangeError: Invalid time value

moment('wtf').toJSON()
> null

Expected behavior
It's annoying when you when to call an api with a nullable field, for example :

this.$store.dispatch('tasks/addTask', {
    title: this.form.title,
    due_at: dayjs(this.form.due_at).second(0)
})

This code does not work if this.form.due_at is "" or null

But this one works :

this.$store.dispatch('tasks/addTask', {
    title: this.form.title,
    due_at: moment(this.form.due_at).second(0)
})

Thank you in advance

Information

• Day.js Version 1.8.15
• OS: macOS 10.14.5
• Browser chrome 75 and firefox 68
• Time zone: Paris

[ghost]

https://runkit.com/embed/tay2fpsxv5bz

moment('').second(0) moment(null).second(0) also return Invalid Date

[g1eny0ung]

@xxyuk I think guillaumebriday means that the toJSON() method would stop the program.

I view the moment.js' source code. It will check the date is valid then choose to call toISOString() or return null.

function toJSON () {
  // new Date(NaN).toJSON() === null
  return this.isValid() ? this.toISOString() : null;
}

Should we also check its validity first by calling isValid()?

[guillaumebriday]

yep exactly @g1eny0ung !

I ended doing this in my own application :

{ due_at: dayjs(this.form.due_at).isValid() ? dayjs(this.form.due_at).second(0) : null }

I will open a PR

[g1eny0ung]

@guillaumebriday 👍