How natural-language dates work in task apps, and where they go wrong

Most modern task apps let you type the date into the task: “pay rent friday”, “call mum tomorrow 6pm”, “renew passport in 3 weeks”. Todoist made this popular, Microsoft To Do and many others have some form of it, and it is the single biggest speed-up in task entry. A date picker takes four clicks; a phrase takes a second.

It also goes wrong in predictable ways. Knowing them saves you from the reminder that fires on the wrong Friday.

What a parser actually does

The app scans your text for something that looks like a date or time, works out the absolute moment it refers to, and removes it from the title. “Call mum tomorrow 6pm” becomes a task called “Call mum” due at 18:00 tomorrow.

Under the hood, many apps use an open-source library for this. Jot uses chrono, a JavaScript parser that handles English phrases like “next Tuesday”, “in 2 hours” and “the 5th at noon”. The hard part is not reading the words. It is deciding what they mean relative to now.

Trap 1: “next Friday”

Said on a Wednesday, does “next Friday” mean the day after tomorrow, or the Friday after that? People disagree, and so do parsers. If it matters, say “this Friday” or “Friday the 9th”.

Trap 2: times without dates

“Call at 3” typed at 4pm. Is that 3am tonight, 3pm tomorrow, or 3pm today (already past)? Most parsers pick the next future occurrence, which means tomorrow afternoon. Usually right, occasionally not. Add the day when the time is close to now.

Trap 3: words that look like dates

“Review the March report” is not due in March. “Call May” is a person. “Fix the 2nd floor printer” is not due on the 2nd. Good apps highlight what they parsed so you can see it before saving, and let you escape it. If the highlight lands on the wrong word, rephrase.

Trap 4: numbers in titles

“Order 3 chairs” and “Book table for 8” can be read as times. Parsers have got much better at this, but it still happens with bare numbers. “Book a table for eight people” avoids it.

Trap 5: day-month order

“4/10” is 4 October in most of the world and April 10 in the US. Parsers usually follow the system locale, which is fine until you travel or work across regions. Spelling out the month removes the ambiguity entirely.

Trap 6: time zones

If you set “3pm” while travelling, is that 3pm where you are or at home? Most desktop apps use the computer’s current time zone at the moment you save. If you change zones often, check how your app behaves before relying on it for a call.

Phrasing that parses reliably

• Put the date at the end: “send invoice to Acme friday 10am”.
• Use day names or “tomorrow” for the next week, and “the 14th” or “14 Oct” beyond that.
• Prefer “10am” over “10”.
• Use “in 2 hours” for short delays.

Check before you save

The habit that prevents every one of these problems is glancing at what the app highlighted before you press save. In Jot, the parsed date shows in the capture box as you type, so a wrong reading is visible in the same second you made it. Four tokens and a date covers the other things Jot reads out of a line - tags, lists and the importance flag.

Jot is on the Microsoft Store. Type the date the way you would say it, and check the highlight.

Jot is a quick-capture app for Windows: one hotkey, one line, back to what you were doing. What it is, or what is still unproven.