The Japanese grammar patterns ~とおりだ, ~とおり(に)..., ~どおりだ, and ~どおり(に)... are used to express that something happens "according to," "just as," or "in the way that" something else was expected or described. These patterns are very common and are used in both written and spoken Japanese.

1. ~とおりだ / ~どおりだ

• Meaning: "It is just as..." or "It is according to..."
• Usage: These patterns are used when you want to say that something is exactly the way it was described or expected.
• Structure:
  • Verb (Dictionary Form) + とおりだ / どおりだ
  • Noun + の + とおりだ / どおりだ
• Examples:
  • 彼が言ったとおりだ。(Kare ga itta toori da) - "It is just as he said."
  • 計画どおりだ。(Keikaku doori da) - "It is according to the plan."

2. ~とおり(に)... / ~どおり(に)...

• Meaning: "In the way that..." or "According to..."
• Usage: These patterns are used to describe that something was done in the way that was previously described or expected.
• Structure:
  • Verb (Dictionary Form) + とおり(に) / どおり(に)
  • Noun + の + とおり(に) / どおり(に)
• Examples:
  • マニュアルのとおりにやってください。(Manyuaru no toori ni yatte kudasai) - "Please do it according to the manual."
  • 予想どおりに試験は難しかった。(Yosou doori ni shiken wa muzukashikatta) - "The exam was difficult just as expected."

Difference Between とおり and どおり

• とおり: This is the standard way to write this phrase. It can be used in both formal and informal contexts.
• どおり: This is a more colloquial or spoken variation and is often seen in everyday conversation. Both forms are interchangeable, but とおり is slightly more formal.

Summary

• ~とおりだ / ~どおりだ: To state that something is exactly as described or expected.
• ~とおり(に)... / ~どおり(に)...: To express that an action is done in accordance with something else, or as expected.

These patterns are very useful when you want to emphasize that something matches a certain expectation, plan, or method.

• によると = "According to" → You are sharing information from a source.