How to fix Cannot use --outDir without specifying file names with .ts extensions in TypeScript

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This TypeScript compilation error occurs when you use the --outDir flag without providing TypeScript source files (.ts or .tsx extensions). The TypeScript compiler needs source files to determine what to compile and where to output the JavaScript files.

What this error means

When you run the TypeScript compiler (tsc) with the --outDir flag, you're telling it to output compiled JavaScript files to a specific directory. However, the compiler needs to know which TypeScript source files to compile. This error typically happens in two scenarios: 1. You're running tsc with --outDir but not specifying any .ts or .tsx files on the command line 2. You're using a tsconfig.json file that doesn't properly specify the files or include patterns The TypeScript compiler requires explicit source files when using --outDir because it needs to know what to compile and where to place the output relative to the source file structure. Without source files, it cannot determine the output directory structure.

How to fix "Cannot use --outDir without specifying file names with .ts extensions"

1Check your tsc command syntax

Verify you're specifying TypeScript source files when using --outDir:

bash

# Correct: Specify .ts files with --outDir
tsc --outDir dist src/*.ts

# Correct: Use tsconfig.json instead
tsc --outDir dist --project tsconfig.json

# Incorrect: Missing .ts files
tsc --outDir dist  # This will cause the error

Always include .ts or .tsx files when using --outDir on the command line.

2Use tsconfig.json for project compilation

Instead of specifying files on the command line, create or use a tsconfig.json file:

json

{
  "compilerOptions": {
    "outDir": "dist",
    "rootDir": "src"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

Then compile with:

bash

tsc
# or
tsc --project tsconfig.json

The tsconfig.json file tells TypeScript which files to compile and where to output them.

3Verify file patterns match TypeScript files

If you're using glob patterns, ensure they match .ts or .tsx files:

bash

# These patterns work with --outDir
tsc --outDir dist src/**/*.ts
tsc --outDir dist *.tsx
tsc --outDir dist app.ts utils.ts

# These will cause errors (no .ts files)
tsc --outDir dist *.js
tsc --outDir dist src/**/*  # Might match non-TypeScript files

Use explicit .ts/.tsx extensions or ensure your glob patterns only match TypeScript files.

4Check tsconfig.json include/exclude patterns

If using tsconfig.json, verify your include patterns match TypeScript files:

json

{
  "compilerOptions": {
    "outDir": "dist"
  },
  "include": [
    "src/**/*.ts",      // Explicit .ts files
    "src/**/*.tsx"      // Explicit .tsx files
  ],
  "exclude": [
    "node_modules",
    "**/*.spec.ts",     // Test files if needed
    "**/*.test.ts"
  ]
}

Common issues:
- "include": ["src"] - includes directories but not file patterns
- "include": ["src/**/*"] - might include non-TypeScript files
- Missing include/exclude sections entirely

5Use the --project flag for specific configurations

When you have multiple tsconfig files or need to specify a configuration:

bash

# Use a specific tsconfig file
tsc --project tsconfig.prod.json

# Compile from a directory containing tsconfig.json
tsc --project ./src

# Build mode for project references
tsc --build --verbose

The --project flag tells TypeScript to use the specified tsconfig.json file or directory containing one.

How to fix Cannot use --outDir without specifying file names with .ts extensions in TypeScript

What this error means

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How to fix "Cannot use --outDir without specifying file names with .ts extensions"

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