とく・
とく and どく are casual spoken contractions of ておく and でおく. They keep the same meanings: doing something in preparation, choosing something for the time being, or leaving a state unchanged.
What the contraction keeps
Only the pronunciation and shape become shorter; the underlying meaning does not change. The action may prepare for something later, maintain a useful state, or express a temporary choice rather than a permanent decision.
Common uses
明日の会議の資料、先に印刷しとくね。
I'll print the materials for tomorrow's meeting in advance.
AnalyzeThe printing is advance preparation for the meeting.
このメール、帰る前に読んどくよ。
I'll read this email before I leave.
Analyzeドアは開けといて。あとで荷物を運ぶから。
Leave the door open. We'll be moving the luggage later.
Analyze開けといて is the casual form of 開けておいて; it asks someone to leave the resulting state unchanged.
A natural past form
明日の店、予約した？
Did you book the restaurant for tomorrow?
Analyzeうん、もう予約しといたよ。
Yeah, I already booked it.
Analyzeしといた is the contracted past form of しておいた.
Do not confuse it with the teru contraction
てる shortens ている and describes an action in progress, a resulting state, or a habit. By contrast, とく shortens ておく and retains the preparation or leave-as-is meaning.
More examples
出かける前に、地図をスマホに保存しとく。
I'll save the map on my phone before going out.
Analyzeこの箱はここに置いといて。
Leave this box here.
Analyze忘れそうだから、今のうちに連絡しといた。
I contacted them while it was on my mind, since I thought I might forget.
Analyze念のため、住所を聞いとかない？
Shouldn't we ask for the address, just in case?
Analyzeこの薬は食後に飲んどけばいいよ。
You just need to take this medicine after eating.
Analyze今回は申し込むのをやめとこう。
Let's decide not to apply this time.
Analyze