> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/BankkRoll/repo2pdf/llms.txt
> Use this file to discover all available pages before exploring further.
# Line Numbers
> Add line numbers to your PDF for easy code reference and navigation
## Overview
Line numbers make it easy to reference specific lines of code in your PDF documentation. repo2pdf can automatically add line numbers to every line of code in your generated PDFs.
## Enabling Line Numbers
When running repo2pdf, you'll be prompted:
```bash theme={null}
repo2pdf
? Would you like to add line numbers? (Y/n)
```
Select **Yes** to add line numbers to your PDF.
## How It Works
Line numbers are added during the PDF generation process:
1. **Counts total lines** in each file
2. **Calculates width** needed for line numbers (handles 1-9999+ lines)
3. **Prepends line number** to each line with proper padding
4. **Maintains alignment** across all lines
From `clone.ts:279-294`:
```typescript theme={null}
const hlData = htmlToJson(highlightedCode, removeEmptyLines);
let lineNum = 1;
const lineNumWidth = hlData
.filter((d) => d.text === "\n")
.length.toString().length;
for (let i = 0; i < hlData.length; i++) {
const { text, color } = hlData[i];
if (i === 0 || hlData[i - 1]?.text === "\n")
if (addLineNumbers) {
doc.text(
String(lineNum++).padStart(lineNumWidth, " ") + " ",
{
continued: true,
textIndent: 0,
},
);
}
doc.fillColor(color || "black");
// ... rest of rendering
}
```
## Dynamic Width Calculation
Line numbers automatically adjust their width based on file size:
**1-9 lines**
Single digit width:
```
1 code
2 code
9 code
```
**10-99 lines**
Two digit width:
```
1 code
10 code
99 code
```
**100+ lines**
Three+ digit width:
```
1 code
100 code
999 code
```
The width is calculated by counting newlines and converting to string length, ensuring perfect alignment.
## Visual Examples
### Without Line Numbers
```typescript theme={null}
function greet(name: string) {
console.log(`Hello, ${name}!`);
}
```
### With Line Numbers
```typescript theme={null}
1 function greet(name: string) {
2 console.log(`Hello, ${name}!`);
3 }
```
## Combined with Other Features
Line numbers work seamlessly with other repo2pdf features:
When both features are enabled:
```typescript theme={null}
1 // Comment in SlateGray
2 function example() {
3 const value = "string in DarkGreen";
4 return 42; // number in OrangeRed
5 }
```
The line numbers remain in black while syntax elements are colored.
When removing empty lines, line numbers skip the blank lines:
**Original:**
```typescript theme={null}
function test() {
return true;
}
```
**With empty lines removed:**
```typescript theme={null}
1 function test() {
2 return true;
3 }
```
Be careful: the line numbers won't match the original file when empty lines are removed!
When Prettier formatting is enabled, line numbers reflect the formatted output:
**Original (unformatted):**
```javascript theme={null}
function test(){return"hello";}
```
**PDF output (formatted with line numbers):**
```javascript theme={null}
1 function test() {
2 return "hello";
3 }
```
Line numbers are added AFTER formatting, so they accurately reflect the PDF content.
## Padding and Alignment
The `padStart()` method ensures consistent alignment:
```typescript theme={null}
String(lineNum++).padStart(lineNumWidth, " ") + " "
```
This means:
* Line 1 becomes `" 1 "` in a 3-digit file (100+ lines)
* Line 10 becomes `" 10 "` in a 3-digit file
* Line 100 becomes `"100 "` in a 3-digit file
The extra space after the line number creates visual separation from the code.
## Use Cases
Reference specific lines when reviewing code: "See line 42 in auth.ts"
Point readers to exact locations in your codebase
Help students follow along with specific line references
Match PDF line numbers with error stack traces
## Performance Considerations
Line number calculation is efficient:
1. **Single pass**: Counts lines while rendering
2. **Minimal overhead**: Simple string operations
3. **No re-parsing**: Uses already-processed syntax data
Adding line numbers typically adds less than 5% to processing time.
## Disabling Line Numbers
If you don't need line numbers, simply answer **No** when prompted:
```bash theme={null}
? Would you like to add line numbers? No
```
The PDF will contain code without line number prefixes.
## Font and Styling
Line numbers use the same monospace font (Courier) as the code:
```typescript theme={null}
doc
.font("Courier")
.fontSize(10)
.text(`${fileName}\n\nBASE64:\n\n${data}`, { lineGap: 4 });
```
This ensures consistent alignment and readability.
## Related Features
Add colors to make code more readable
Add page numbers to your PDF footer