JavaScript AST Visualizer & Explorer
Parse and explore JavaScript code as an interactive Abstract Syntax Tree. Paste or upload any JS code to see its parsed tree structure with color-coded node types, expandable branches, detailed properties, and node type filtering. Perfect for understanding code structure, analyzing obfuscated scripts, and learning how JavaScript parsers work.
Parse JavaScript code into an interactive Abstract Syntax Tree. Paste your code below, then explore the tree by expanding nodes and clicking to inspect properties.
Click any AST node to view its properties
Why Use Our JavaScript AST Visualizer?
Instant AST Visualization
Parse any JavaScript code and visualize its Abstract Syntax Tree instantly as an interactive tree. Paste or upload JS code and immediately see the parsed structure with color-coded node types, expandable branches, and detailed property information for each node. All parsing happens locally in your browser.
Secure & Private Code Analysis
Your JavaScript source code never leaves your device. All parsing, tree generation, and AST analysis happens entirely in your browser using pure JavaScript. No uploads, no tracking, no server-side processing - complete privacy for all code you analyze.
JS AST Explorer Online - No Installation
Use the JavaScript AST visualizer directly in any modern browser with no downloads, apps, or plugins required. Works offline after first load and handles any size of JavaScript input. 100% free forever with no signup required.
Interactive Tree Navigation & Filtering
Navigate complex AST trees with expandable/collapsible nodes, search by node type, and view detailed properties for any selected node. Color-coded node types make it easy to identify function declarations, variable declarations, expressions, and more at a glance.
Common Use Cases for JavaScript AST Visualizer
JavaScript Source Code Analysis
Developers use the AST visualizer to understand the structure of JavaScript source code by viewing its parsed tree representation. See how the parser interprets your code, identify ambiguous constructs, and verify that your code structure matches your intent.
Obfuscated Code Reverse Engineering
Security researchers and reverse engineers use the AST visualizer to analyze obfuscated JavaScript code. By viewing the parsed tree structure, hidden patterns, encoded strings, and control flow modifications become visible even when the source code is intentionally obscured.
Programming Education & Learning
Students and educators use the JavaScript AST visualizer to learn how JavaScript parsers interpret code. The visual tree representation makes abstract concepts like hoisting, scope, and expression evaluation tangible by showing exactly how the parser structures each construct.
Code Linting & Syntax Verification
Quality assurance engineers use the AST visualizer to verify that code is syntactically valid and structured as expected. The parsed tree reveals syntax errors, unexpected nesting, and structural problems that might be missed when reading source code directly.
Code Transformation & Tool Development
Developers building code transformation tools, linters, or minifiers use the AST visualizer to understand how their target code will be parsed. See the exact node types, positions, and properties produced by the parser to write accurate transformation logic.
Security Audit & Vulnerability Analysis
Security auditors use the JavaScript AST visualizer to analyze potentially malicious code. The parsed tree reveals eval() calls, dynamic property access, suspicious function constructions, and other patterns that may indicate code injection or obfuscation attempts.
Understanding JavaScript AST Visualization
What is a JavaScript Abstract Syntax Tree (AST)?
An Abstract Syntax Tree (AST) is a tree representation of the syntactic structure of JavaScript source code. Each node in the tree represents a construct occurring in the source code - such as a function declaration,variable declaration, binary expression, orif statement. The tree structure captures the hierarchical relationships between these constructs, showing which nodes are children of others.
ASTs are the foundation for most code analysis tools - compilers, linters (ESLint), formatters (Prettier), minifiers (Terser), and obfuscators all work by parsing source code into an AST, transforming it, and generating new code from the modified tree. Our JavaScript AST visualizer makes this internal representation visible and explorable, helping you understand exactly how a parser interprets your code structure.
How Our JavaScript AST Visualizer Works
- 1. Lexical Analysis (Tokenization): The tool first breaks your JavaScript source code into tokens - the smallest meaningful units like keywords (
function,const,if), identifiers (variable and function names), operators (+,=,=>), and punctuation ((,{,;). Each token is tagged with its type and position in the source. - 2. Syntactic Parsing: The token stream is then parsed according to JavaScript grammar rules to build the Abstract Syntax Tree. The parser recognizes language constructs like function declarations, class definitions, variable declarations, loops, conditionals, and expressions, organizing them into a hierarchical tree structure where parent nodes contain child nodes that represent their constituent parts.
- 3. Tree Rendering & Interaction: The parsed AST is rendered as an interactive collapsible tree. Each node is color-coded by its type category (declarations, statements, expressions, patterns), and clicking a node reveals its detailed properties including type, position (line/column), and child references. You can expand and collapse branches, search by node type, and explore the full tree structure.
Key AST Node Types & Categories
- Program: The root node representing the entire JavaScript file. Contains a body array with all top-level statements, including imports, function declarations, class declarations, and variable declarations.
- Declarations: Nodes representing named constructs -FunctionDeclaration (function with name, params, body),VariableDeclaration (const/let/var with declarators),ClassDeclaration (class with body, superClass),ImportDeclaration and ExportDeclaration.
- Statements: Nodes representing executable statements -ExpressionStatement, IfStatement,ForStatement, WhileStatement,ReturnStatement, TryStatement,SwitchStatement, and more.
- Expressions: Nodes representing values and operations -BinaryExpression (a + b), CallExpression (foo()),MemberExpression (a.b), ArrowFunctionExpression,ArrayExpression, ObjectExpression,Literal, Identifier, and TemplateLiteral.
Using the AST Explorer for Code Analysis
The JavaScript AST visualizer is an essential tool for anyone working with code analysis, transformation, or obfuscation. When analyzing obfuscated code, the AST reveals structural patterns that are hidden in the source - encoded strings appear asCallExpression nodes with specific argument patterns, control flow flattening shows as SwitchStatement or WhileStatementwrappers, and dead code injection appears as unreachable branches in the tree.
For learning purposes, the AST visualizer helps bridge the gap between how you write code and how the parser interprets it. Experiment with different JavaScript constructs to see how they map to tree nodes - you will notice how arrow functionsvs regular functions produce different AST structures, or howdestructuring creates nested pattern nodes. All processing is done locally in your browser with no data sent to external servers.