# Debugger API Reference
## Types
```ts
import type { ICDPSession } from './cdp-session.js';
export interface BreakpointInfo {
id: string;
file: string;
line: number;
}
export interface LocationInfo {
url: string;
lineNumber: number;
columnNumber: number;
callstack: Array<{
functionName: string;
url: string;
lineNumber: number;
columnNumber: number;
}>;
sourceContext: string;
}
export interface EvaluateResult {
value: unknown;
}
export interface ScriptInfo {
scriptId: string;
url: string;
}
/**
* A class for debugging JavaScript code via Chrome DevTools Protocol.
* Works with both Node.js (--inspect) and browser debugging.
*
* @example
* ```ts
* const cdp = await getCDPSessionForPage({ page, wsUrl })
* const dbg = new Debugger({ cdp })
*
* await dbg.setBreakpoint({ file: 'https://example.com/app.js', line: 42 })
* // trigger the code path, then:
* const location = await dbg.getLocation()
* const vars = await dbg.inspectLocalVariables()
* await dbg.resume()
* ```
*/
export declare class Debugger {
private cdp;
private debuggerEnabled;
private paused;
private currentCallFrames;
private breakpoints;
private scripts;
private xhrBreakpoints;
private blackboxPatterns;
/**
* Creates a new Debugger instance.
*
* @param options - Configuration options
* @param options.cdp - A CDPSession instance for sending CDP commands (works with both
* our CDPSession and Playwright's CDPSession)
*
* @example
* ```ts
* const cdp = await getCDPSessionForPage({ page, wsUrl })
* const dbg = new Debugger({ cdp })
* ```
*/
constructor({ cdp }: {
cdp: ICDPSession;
});
private setupEventListeners;
/**
* Enables the debugger and runtime domains. Called automatically by other methods.
* Also resumes execution if the target was started with --inspect-brk.
*
* @example
* ```ts
* await dbg.enable()
* ```
*/
enable(): Promise<void>;
/**
* Sets a breakpoint at a specified URL and line number.
* Use the URL from listScripts() to find available scripts.
*
* @param options - Breakpoint options
* @param options.file - Script URL (e.g. https://example.com/app.js)
* @param options.line - Line number (1-based)
* @param options.condition - Optional JS expression; only pause when it evaluates to true
* @returns The breakpoint ID for later removal
*
* @example
* ```ts
* const id = await dbg.setBreakpoint({ file: 'https://example.com/app.js', line: 42 })
* // later:
* await dbg.deleteBreakpoint({ breakpointId: id })
*
* // Conditional breakpoint - only pause when userId is 123
* await dbg.setBreakpoint({
* file: 'https://example.com/app.js',
* line: 42,
* condition: 'userId === 123'
* })
* ```
*/
setBreakpoint({ file, line, condition }: {
file: string;
line: number;
condition?: string;
}): Promise<string>;
/**
* Removes a breakpoint by its ID.
*
* @param options - Options
* @param options.breakpointId - The breakpoint ID returned by setBreakpoint
*
* @example
* ```ts
* await dbg.deleteBreakpoint({ breakpointId: 'bp-123' })
* ```
*/
deleteBreakpoint({ breakpointId }: {
breakpointId: string;
}): Promise<void>;
/**
* Returns a list of all active breakpoints set by this debugger instance.
*
* @returns Array of breakpoint info objects
*
* @example
* ```ts
* const breakpoints = dbg.listBreakpoints()
* // [{ id: 'bp-123', file: 'https://example.com/index.js', line: 42 }]
* ```
*/
listBreakpoints(): BreakpointInfo[];
/**
* Inspects local variables in the current call frame.
* Must be paused at a breakpoint. String values over 1000 chars are truncated.
* Use evaluate() for full control over reading specific values.
*
* @returns Record of variable names to values
* @throws Error if not paused or no active call frames
*
* @example
* ```ts
* const vars = await dbg.inspectLocalVariables()
* // { myVar: 'hello', count: 42 }
* ```
*/
inspectLocalVariables(): Promise<Record<string, unknown>>;
/**
* Returns global lexical scope variable names.
*
* @returns Array of global variable names
*
* @example
* ```ts
* const globals = await dbg.inspectGlobalVariables()
* // ['myGlobal', 'CONFIG']
* ```
*/
inspectGlobalVariables(): Promise<string[]>;
/**
* Evaluates a JavaScript expression and returns the result.
* When paused at a breakpoint, evaluates in the current stack frame scope,
* allowing access to local variables. Otherwise evaluates in global scope.
* Values are not truncated, use this for full control over reading specific variables.
*
* @param options - Options
* @param options.expression - JavaScript expression to evaluate
* @returns The result value
*
* @example
* ```ts
* // When paused, can access local variables:
* const result = await dbg.evaluate({ expression: 'localVar + 1' })
*
* // Read a large string that would be truncated in inspectLocalVariables:
* const full = await dbg.evaluate({ expression: 'largeStringVar' })
* ```
*/
evaluate({ expression }: {
expression: string;
}): Promise<EvaluateResult>;
/**
* Gets the current execution location when paused at a breakpoint.
* Includes the call stack and surrounding source code for context.
*
* @returns Location info with URL, line number, call stack, and source context
* @throws Error if debugger is not paused
*
* @example
* ```ts
* const location = await dbg.getLocation()
* console.log(location.url) // 'https://example.com/src/index.js'
* console.log(location.lineNumber) // 42
* console.log(location.callstack) // [{ functionName: 'handleRequest', ... }]
* console.log(location.sourceContext)
* // ' 40: function handleRequest(req) {
* // 41: const data = req.body
* // > 42: processData(data)
* // 43: }'
* ```
*/
getLocation(): Promise<LocationInfo>;
/**
* Steps over to the next line of code, not entering function calls.
*
* @throws Error if debugger is not paused
*
* @example
* ```ts
* await dbg.stepOver()
* const newLocation = await dbg.getLocation()
* ```
*/
stepOver(): Promise<void>;
/**
* Steps into a function call on the current line.
*
* @throws Error if debugger is not paused
*
* @example
* ```ts
* await dbg.stepInto()
* const location = await dbg.getLocation()
* // now inside the called function
* ```
*/
stepInto(): Promise<void>;
/**
* Steps out of the current function, returning to the caller.
*
* @throws Error if debugger is not paused
*
* @example
* ```ts
* await dbg.stepOut()
* const location = await dbg.getLocation()
* // back in the calling function
* ```
*/
stepOut(): Promise<void>;
/**
* Resumes code execution until the next breakpoint or completion.
*
* @throws Error if debugger is not paused
*
* @example
* ```ts
* await dbg.resume()
* // execution continues
* ```
*/
resume(): Promise<void>;
/**
* Returns whether the debugger is currently paused at a breakpoint.
*
* @returns true if paused, false otherwise
*
* @example
* ```ts
* if (dbg.isPaused()) {
* const vars = await dbg.inspectLocalVariables()
* }
* ```
*/
isPaused(): boolean;
/**
* Configures the debugger to pause on exceptions.
*
* @param options - Options
* @param options.state - When to pause: 'none' (never), 'uncaught' (only uncaught), or 'all' (all exceptions)
*
* @example
* ```ts
* // Pause only on uncaught exceptions
* await dbg.setPauseOnExceptions({ state: 'uncaught' })
*
* // Pause on all exceptions (caught and uncaught)
* await dbg.setPauseOnExceptions({ state: 'all' })
*
* // Disable pausing on exceptions
* await dbg.setPauseOnExceptions({ state: 'none' })
* ```
*/
setPauseOnExceptions({ state }: {
state: 'none' | 'uncaught' | 'all';
}): Promise<void>;
/**
* Lists available scripts where breakpoints can be set.
* Automatically enables the debugger if not already enabled.
*
* @param options - Options
* @param options.search - Optional string to filter scripts by URL (case-insensitive)
* @returns Array of up to 20 matching scripts with scriptId and url
*
* @example
* ```ts
* // List all scripts
* const scripts = await dbg.listScripts()
* // [{ scriptId: '1', url: 'https://example.com/app.js' }, ...]
*
* // Search for specific files
* const handlers = await dbg.listScripts({ search: 'handler' })
* // [{ scriptId: '5', url: 'https://example.com/handlers.js' }]
* ```
*/
listScripts({ search }?: {
search?: string;
}): Promise<ScriptInfo[]>;
setXHRBreakpoint({ url }: {
url: string;
}): Promise<void>;
removeXHRBreakpoint({ url }: {
url: string;
}): Promise<void>;
listXHRBreakpoints(): string[];
/**
* Sets regex patterns for scripts to blackbox (skip when stepping).
* Blackboxed scripts are hidden from the call stack and stepped over automatically.
* Useful for ignoring framework/library code during debugging.
*
* @param options - Options
* @param options.patterns - Array of regex patterns to match script URLs
*
* @example
* ```ts
* // Skip all node_modules
* await dbg.setBlackboxPatterns({ patterns: ['node_modules'] })
*
* // Skip React and other frameworks
* await dbg.setBlackboxPatterns({
* patterns: [
* 'node_modules/react',
* 'node_modules/react-dom',
* 'node_modules/next',
* 'webpack://',
* ]
* })
*
* // Skip all third-party scripts
* await dbg.setBlackboxPatterns({ patterns: ['^https://cdn\\.'] })
*
* // Clear all blackbox patterns
* await dbg.setBlackboxPatterns({ patterns: [] })
* ```
*/
setBlackboxPatterns({ patterns }: {
patterns: string[];
}): Promise<void>;
/**
* Adds a single regex pattern to the blackbox list.
*
* @param options - Options
* @param options.pattern - Regex pattern to match script URLs
*
* @example
* ```ts
* await dbg.addBlackboxPattern({ pattern: 'node_modules/lodash' })
* await dbg.addBlackboxPattern({ pattern: 'node_modules/axios' })
* ```
*/
addBlackboxPattern({ pattern }: {
pattern: string;
}): Promise<void>;
/**
* Removes a pattern from the blackbox list.
*
* @param options - Options
* @param options.pattern - The exact pattern string to remove
*/
removeBlackboxPattern({ pattern }: {
pattern: string;
}): Promise<void>;
/**
* Returns the current list of blackbox patterns.
*/
listBlackboxPatterns(): string[];
private truncateValue;
private formatPropertyValue;
private processRemoteObject;
}
```
## Examples
```ts
import { page, getCDPSession, createDebugger, console } from './debugger-examples-types.js'
// Example: List available scripts and set a breakpoint
async function listScriptsAndSetBreakpoint() {
const cdp = await getCDPSession({ page })
const dbg = createDebugger({ cdp })
await dbg.enable()
const scripts = await dbg.listScripts({ search: 'app' })
console.log(scripts)
if (scripts.length > 0) {
const bpId = await dbg.setBreakpoint({ file: scripts[0].url, line: 100 })
console.log('Breakpoint set:', bpId)
}
}
// Example: Inspect state when paused at a breakpoint
async function inspectWhenPaused() {
const cdp = await getCDPSession({ page })
const dbg = createDebugger({ cdp })
await dbg.enable()
if (dbg.isPaused()) {
const loc = await dbg.getLocation()
console.log('Paused at:', loc.url, 'line', loc.lineNumber)
console.log('Source:', loc.sourceContext)
const vars = await dbg.inspectLocalVariables()
console.log('Variables:', vars)
const result = await dbg.evaluate({ expression: 'myVar.length' })
console.log('myVar.length =', result.value)
await dbg.stepOver()
}
}
// Example: Step through code
async function stepThroughCode() {
const cdp = await getCDPSession({ page })
const dbg = createDebugger({ cdp })
await dbg.enable()
await dbg.setBreakpoint({ file: 'https://example.com/app.js', line: 42 })
if (dbg.isPaused()) {
await dbg.stepOver()
await dbg.stepInto()
await dbg.stepOut()
await dbg.resume()
}
}
// Example: Cleanup all breakpoints
async function cleanupBreakpoints() {
const cdp = await getCDPSession({ page })
const dbg = createDebugger({ cdp })
const breakpoints = dbg.listBreakpoints()
for (const bp of breakpoints) {
await dbg.deleteBreakpoint({ breakpointId: bp.id })
}
}
export { listScriptsAndSetBreakpoint, inspectWhenPaused, stepThroughCode, cleanupBreakpoints }
```
