Range formatting of imports introduces extra spacing

[denbezrukov]

Your Environment

• Prettier version: 3.5.3
• node version: 20
• package manager: npm@10
• IDE: WebStorm & CLI

Describe the bug

When using --range-start / --range-end to format for example a single import statement.
Extra blank lines are added after the import.

To Reproduce

1. Install dependencies:

   {
     "devDependencies": {
       "@ianvs/prettier-plugin-sort-imports": "^4.4.1",
       "prettier": "^3.5.3",
       "typescript": "^5.4.3"
     },
   }

2. Create a file hello.ts:

import { Component, OnInit } from "@angular/core";

//

3. Create config

trailingComma: "es5"
semi: true
singleQuote: false
arrowParens: always
bracketSpacing: true
quoteProps: as-needed
htmlWhitespaceSensitivity: ignore
plugins:
  - "@ianvs/prettier-plugin-sort-imports"
importOrderParserPlugins:
  - "typescript"
  - "classProperties"
  - "decorators"
importOrder:
  - "^@angular(/.*)?$"
  - ""
  - "^primeng(/.*)?$"
  - ""
  - <THIRD_PARTY_MODULES>
  - ""
  - "^@app(/.*)?$"
  - ""
  - "^(\\.).*$"
importOrderTypeScriptVersion: 4.7.4

4. Run Prettier with this command:

prettier --range-start=0 --range-end=53 hello.ts

5. Actual output:

import { Component, OnInit } from "@angular/core";



//

Expected behavior

import { Component, OnInit } from "@angular/core";

//

Error log

No error — just unexpected formatting.

[fbartho]

This is the first time I hear about this feature from prettier! Do you know when it’s used?

This plugin certainly relies on prettier stripping extra blank-lines from the output, and it looks like that feature of prettier is disabled when you use the range-formatting flags.

I’m not sure how we would fix this without re-implementing that logic ourselves, and at first glance, I’m not sure our plugin should implement that logic.

That said, I think we probably could run a final pass over our output to find/replace strings of newlines with single newlines, so the fix might be minor?

[IanVS]

@denbezrukov does this behavior happen no matter the importOrder that you use, and the type of imports that you are sorting, or does it only happen in some situations?

[denbezrukov]

@IanVS @fbartho

Thanks for your response!

I've tried different importOrder settings, and all of them add an extra line when formatting a range:

importOrder:
  - "^@angular(/.*)?$"
  - "^(\\.).*$"

importOrder:
  - <THIRD_PARTY_MODULES>
  - "^(\\.).*$"

We've encountered this issue when users use Prettier with the sorting plugin:

• To optimize imports – IDEA calls formatting with a range after optimizing.
• Then, the range to format is not related to imports, for example.

import { Component, OnInit } from "@angular/core";

//


class Hello {}

I intended to format only the class, but it seems that the preprocessor adds an extra line after the import.

To be honest, I'm not entirely sure how to fix this properly.
As far as I understand, plugins can't extend the formatting range.
A possible temporary solution might be to disable the plugin when Prettier is formatting a specific range.

What do you think?

[IanVS]

A possible temporary solution might be to disable the plugin when Prettier is formatting a specific range.

That actually sounds reasonable to me, assuming we have access to that information in the plugin (I assume we do, but haven't looked into it yet). We don't use/respect prettier range information, so the safest thing to do is probably nothing, unless we wanted to find a way to respect the range (which would be non-trivial).

However, it sounds like in this case if I understand correctly, IDEA is only ever triggering prettier with ranges (once for the imports, and thereafter only for smaller sections of code), is that correct? So IDEA users who install this plugin would probably think it is broken, which is unfortunate.

[denbezrukov]

@IanVS
Yeah, you’re right.
As far as I know, IDEA triggers range formatting during “Optimize Imports” and when users select a piece of code and trigger formatting on that selection.
The plugin won’t work if we implement a solution that skips the plugin for range formatting; however, it will still work on save or when formatting the entire file.
If that’s okay, I can try to create a PR with the proposed solution.

[IanVS]

That sounds good to me, thanks @denbezrukov!

[fbartho]

@denbezrukov as an alternative: if you wanted to try to determine if there are excess newlines to be dropped, you could try to patch something in here:

prettier-plugin-sort-imports/src/utils/get-sorted-nodes.ts

Lines 84 to 86 in ddad06c

	if (finalNodes.length > 0) {
	finalNodes.push(newLineNode);
	}

It wouldn't be easy (perf-wise), so I'd make it conditional to only execute when the range-formatting feature of prettier is active.

---

The more I think about this, the more I think this is a bug in Prettier itself. Prettier is responsible for stripping excess newlines. I would highly recommend you file a ticket on Prettier core Prettier doesn't strip excess newlines when formatting with selected range CLI parameters (I haven't tested this in isolation, however)

[fbartho]

I did some quick research, and there's no detectable-in-options obvious way to tell if you are in "range-formatting-mode".

Here's the diff of the options:

--- tmp1.txt    2025-05-29 16:36:15
+++ tmp2.txt    2025-05-29 16:36:53
@@ -1,6 +1,6 @@
 
-> @ianvs/prettier-plugin-sort-imports@4.4.2 format
-> prettier . --write
+> @ianvs/prettier-plugin-sort-imports@4.4.2 test:range-format-unit-test:format
+> prettier --range-start=0 --range-end=53 ./tests/RangeFormatting/orig.ts
 
 {
   endOfLine: 'lf',
@@ -22,7 +22,9 @@
   ],
   importOrder: [ '', '<BUILTIN_MODULES>', '', '<THIRD_PARTY_MODULES>', '', '^[./]' ],
   importOrderTypeScriptVersion: '5.0.0',
-  filepath: '/Users/fbarthelemy/Code/prettier-plugin-sort-imports/src/preprocessors/default.ts',
+  rangeEnd: 53,
+  rangeStart: 0,
+  filepath: '/Users/fbarthelemy/Code/prettier-plugin-sort-imports/tests/RangeFormatting/orig.ts',
   parser: 'typescript',
   bracketSpacing: true,
   htmlWhitespaceSensitivity: 'css',
@@ -39,8 +41,6 @@
   importOrderCaseSensitive: false,
   cursorOffset: -1,
   insertPragma: false,
-  rangeEnd: 300,
-  rangeStart: 0,
   requirePragma: false,
   embeddedLanguageFormatting: 'auto',
   astFormat: 'estree',
@@ -63,4 +63,10 @@
   },
   originalText: undefined
 }

If Idea always formats the top 53 lines of the file, we could use that as a heuristic, or inversely if options.rangeEnd === file.lines.length. But I don't love those heuristics.

This makes me all the more certain this is a bug in prettier core that it's not stripping the blank-lines when range !== totalLines.

I was hoping to make a reproducible test case to submit to Prettier's issue tracker that doesn't require our plugin, but I won't have time to do that.

#214 contains some snippets that could be turned into a test-case for this issue.