The deno lint command analyzes your source code for potential errors and style issues.
Usage
deno lint [OPTIONS] [FILES]...
Basic Examples
# Lint all files in current directory
deno lint
# Lint specific files
deno lint src/main.ts
# Lint and auto-fix issues
deno lint --fix
# List all available rules
deno lint --rules
# Output as JSON
deno lint --json
Rule Management
List all available lint rules Show rules from specific tagsdeno lint --rules --rules-tags=recommended
Include specific rulesdeno lint --rules-include=no-unused-vars,no-debugger
Exclude specific rulesdeno lint --rules-exclude=no-explicit-any,ban-types
Auto-fix
Automatically fix lint issues where possible# Fix all auto-fixable issues
deno lint --fix
# Fix specific files
deno lint --fix src/main.ts
Output lint results as JSONdeno lint --json > lint-results.json
Watch Mode
Watch for file changes and re-lint automatically# Watch mode
deno lint --watch
# Watch specific paths
deno lint --watch=src/
Don’t clear the screen on watch mode restart
File Filtering
Ignore files or directoriesdeno lint --ignore=build/,dist/,**/*_test.ts
Configuration
Configure linting in deno.json:
{
"lint": {
"include": ["src/"],
"exclude": ["src/testdata/", "build/"],
"rules": {
"tags": ["recommended"],
"include": ["ban-untagged-todo"],
"exclude": ["no-unused-vars"]
}
}
}
Common Rules
Recommended Rules
no-unused-vars - Disallow unused variablesno-debugger - Disallow debugger statementsno-explicit-any - Disallow explicit any typeno-undef - Disallow undefined variablesno-unreachable - Disallow unreachable codeeqeqeq - Require === and !==no-empty - Disallow empty block statementsno-prototype-builtins - Disallow calling built-in object methods directlyno-throw-literal - Disallow throwing non-Error valuesprefer-as-const - Prefer as const over literal type
Fresh-Specific Rules
fresh-server-event-handlers - Validate Fresh server event handlersfresh-handler-export - Ensure Fresh handlers are exported correctly
Ignoring Code
Ignore File
Add a comment at the top of the file:
// deno-lint-ignore-file
function problematic() {
var x = 1; // normally would warn about 'var'
}
Ignore Next Line
// deno-lint-ignore no-unused-vars
const unused = "this variable is not used";
Ignore Multiple Rules
// deno-lint-ignore no-explicit-any no-unused-vars
const data: any = {};
Ignore in Configuration
{
"lint": {
"rules": {
"exclude": ["no-explicit-any", "no-unused-vars"]
}
}
}
Examples
Lint with Auto-fix in CI
#!/bin/bash
# Check if linting would make changes
if ! deno lint --check; then
echo "Linting issues found. Run 'deno lint --fix' to fix them."
exit 1
fi
Custom Rule Configuration
{
"lint": {
"rules": {
"tags": ["recommended"],
"include": [
"ban-untagged-todo",
"camelcase",
"explicit-function-return-type"
],
"exclude": [
"no-explicit-any"
]
}
}
}
Lint Specific File Types
# Lint only TypeScript files
deno lint **/*.ts
# Lint excluding test files
deno lint --ignore="**/*_test.ts"
Output Lint Results
# Generate JSON report
deno lint --json > lint-report.json
# Compact output for CI
deno lint --compact src/
Pre-commit Hook
#!/bin/bash
# .git/hooks/pre-commit
if ! deno lint; then
echo "Please fix linting issues before committing"
exit 1
fi