By the way - comma

[Nightmare85]

Hello
I would like to know if I should use all commas:
By the way, I read the exact same thing yesterday.
I have already heard about his choice, which is, by the way, very sad.
You misspelled my name, by the way.

I believe that I should definitely use commas for the 2nd sentence.
What about sentence 1 and 3?

Cheers!

 

[TP09]

Hello
I would like to know if I should use all commas:
By the way, I read the exact same thing yesterday.
I have already heard about his choice, which is, by the way, very sad.
You misspelled my name, by the way.

I believe that I should definitely use commas for the 2nd sentence.
What about sentence 1 and 3?

Cheers!

**Not a teacher**

You are correct, commas should be used in all three sentences.

 

[sarat_106]

Hello
I would like to know if I should use all commas:
By the way, I read the exact same thing yesterday.
I have already heard about his choice, which is by the way, very sad.
You misspelled my name, by the way.

I believe that I should definitely use commas for the 2nd sentence.
What about sentence 1 and 3?

Cheers!

I do not think, you need a comma before ‘by the way’ in the second sentence as because it is a phrase functioning as adverb. Let us replace ‘by the way’ by another adverb ‘incidentally’ which means the same, see whether it sounds natural.
I have already heard about his choice, which is incidentally, very sad.
Please remember, where there is a pause in a sentence and an additional phrase(here it is ‘very sad’) is added, a comma precedes that insertion and is placed to complete it. As a practice, speak it.aloud and you will know if the sentence needs that pause.

 

[Raymott]

Yes, you need them all.

You also need one here:
I have already heard about his choice, which is, incidentally, very sad.
If you don't put a comma before 'incidentally', why would you put one after it? If you removed 'incidentally', you'd have:
"... which is, very sad." which isn't right.

Speaking sentences aloud won't help with mandatory commas. This is only good for optional commas.