Hvis det ikke havde regnet, ville jeg have hængt skjorterne på tørresnoren i går.

It is a past counterfactual conditional.

That means the speaker is talking about:

• a condition that was not fulfilled in the past
• a result that therefore did not happen

So the sentence implies:

• it did rain
• because of that, the speaker did not hang the shirts out yesterday

A very common Danish pattern for this is:

• Hvis + past perfect
• ville + have + past participle

Because hvis introduces a subordinate clause, and Danish word order changes in subordinate clauses.

In a subordinate clause, sentence adverbs like ikke usually come before the finite verb.

So you get:

• Hvis det ikke havde regnet

But in a main clause, you would normally say:

• Det havde ikke regnet

This is a very important Danish word-order difference:

• main clause: subject + verb + ikke
• subordinate clause: subject + ikke
  • verb

Havde regnet is the past perfect.

It is used here because the raining is the unreal condition that comes before the imagined result.

Timeline:

• first: the weather situation yesterday
• then: the possible action of hanging the shirts out

So Danish uses havde + past participle to mark that earlier past condition:

• havde regnet = had rained

In counterfactual past sentences, this is the normal form after hvis.

Because Danish main clauses follow the verb-second rule, often called V2.

When the sentence starts with the hvis clause, that whole clause takes the first position. Then the finite verb of the main clause must come next.

So the structure is:

• Hvis det ikke havde regnet = first element
• ville = second-position verb
• jeg = subject

That is why you get:

• Hvis det ikke havde regnet, ville jeg ...

If the main clause stood alone, it would be:

• Jeg ville have hængt skjorterne på tørresnoren i går

Because Danish uses ville have + past participle to express a hypothetical result in the past.

So:

• ville hænge = would hang
• ville have hængt = would have hung

Here the speaker is not talking about a present or future possibility, but about something that would have happened yesterday.

That is why the sentence uses:

• ville jeg have hængt

Hængt is the past participle of hænge in this sentence.

After have, Danish normally uses the past participle:

• have regnet
• have hængt

So have hængt works like English have hung.

Not if you want the same clear meaning.

Hvis det ikke regnede would normally suggest a more present, general, or less specifically past situation. It does not fit as naturally with i går and with this clear counterfactual-about-yesterday meaning.

For a past unreal condition, Danish normally prefers:

• Hvis det ikke havde regnet, ville jeg have hængt ...

So for this sentence, havde regnet is the natural choice.

Because Danish uses det as a dummy subject with weather expressions, just like English uses it.

Examples:

• Det regner = it is raining
• Det sneede = it snowed
• Det havde regnet = it had rained

The det does not refer to a thing. It is just required by the grammar.

Because skjorterne is the definite plural form, meaning the shirts.

Forms:

• en skjorte = a shirt
• skjorten = the shirt
• skjorter = shirts
• skjorterne = the shirts

So the sentence is referring to specific shirts, not just shirts in general.

Tørresnoren is a compound noun, which is very common in Danish.

It is built from:

• tørre = dry
• snor = string, line

Together:

• tørresnor = clothesline
• tørresnoren = the clothesline

And:

• på tørresnoren = on the clothesline

Danish often joins nouns into one word where English uses two words.

That is a very normal place for a time expression in Danish.

The end position is neutral and natural here:

• ville jeg have hængt skjorterne på tørresnoren i går

You can sometimes move time expressions for emphasis, but the final position is common and easy.

So this placement does not mean anything unusual. It is just standard sentence rhythm.

Historically, yes, ville is related to vil, but in sentences like this it functions much like English would.

Compare:

• Jeg vil gøre det = I want to do it / I will do it
• Jeg ville gøre det = I would do it / I wanted to do it, depending on context
• Jeg ville have gjort det = I would have done it

So in this sentence, ville is part of the conditional meaning, not just a simple past tense.

Because the sentence begins with a subordinate hvis clause, and Danish normally separates that clause from the main clause with a comma.

So the structure is:

• Hvis det ikke havde regnet, = subordinate clause
• ville jeg have hængt skjorterne på tørresnoren i går. = main clause

That comma is expected and standard here.