Abstract syntax tree classes for working with JavaScript and TypeScript programs¶

CodeQL has a large selection of classes for representing the abstract syntax tree of JavaScript and TypeScript programs.

The abstract syntax tree (AST) represents the syntactic structure of a program. Nodes on the AST represent elements such as statements and expressions.

Statement classes¶

This table lists subclasses of Stmt representing ECMAScript and TypeScript statements.

Statement syntax	CodeQL class	Superclasses	Remarks
Expr `;`	ExprStmt
Label `:` Stmt	LabeledStmt
`;`	EmptyStmt
`break` Label `;`	BreakStmt	JumpStmt, BreakOrContinueStmt
`case` Expr `:` Stmt…	Case		can only occur as child of a SwitchStmt
`catch(` Identifier `)` `{` Stmt… `}`	CatchClause	ControlStmt	can only occur as child of a TryStmt
`class` Identifier `extends` Expr `{` MemberDeclaration… `}`	ClassDeclStmt	ClassDefinition, ClassOrInterface, TypeParameterized
`const` Identifier `=` Expr `;`	ConstDeclStmt	DeclStmt
`continue` Label `;`	ContinueStmt	JumpStmt, BreakOrContinueStmt
`debugger;`	DebuggerStmt
`declare` `global` `{` Stmt… `}`	GlobalAugmentationDeclaration
`declare` `module` StringLiteral `{` Stmt… `}`	ExternalModuleDeclaration
`default:` Stmt…	Case		can only occur as child of a SwitchStmt; use isDefault to distinguish default from case
`do` Stmt `while` `(` Expr `)`	DoWhileStmt	ControlStmt, LoopStmt
`enum` Identifier `{` MemberDeclaration… `}`	EnumDeclaration	NamespaceDefinition
`export * from` StringLiteral	BulkReExportDeclaration	ReExportDeclaration, ExportDeclaration
`export default` ClassDeclStmt	ExportDefaultDeclaration	ExportDeclaration
`export default` Expr `;`	ExportDefaultDeclaration	ExportDeclaration
`export default` FunctionDeclStmt	ExportDefaultDeclaration	ExportDeclaration
`export {` ExportSpecifier… `};`	ExportNamedDeclaration	ExportDeclaration
`export` DeclStmt	ExportNamedDeclaration	ExportDeclaration
`export` `=` Expr `;`	ExportAssignDeclaration
`export` `as` `namespace` Identifier `;`	ExportAsNamespaceDeclaration
`for` `(` Expr `;` Expr `;` Expr `)` Stmt	ForStmt	ControlStmt, LoopStmt
`for` `(` VarAccess `in` Expr `)` Stmt	ForInStmt	ControlStmt, LoopStmt, EnhancedForLoop
`for` `(` VarAccess `of` Expr `)` Stmt	ForOfStmt	ControlStmt, LoopStmt, EnhancedForLoop
`function` Identifier `(` Parameter… `)` `{` Stmt… `}`	FunctionDeclStmt	Function
`if` `(` Expr `)` Stmt `else` Stmt	IfStmt	ControlStmt
`import {` ImportSpecifier… `from` StringLiteral	ImportDeclaration	Import
`import` Identifier `=` Expr `;`	ImportEqualsDeclaration
`interface` Identifier `{` MemberDeclaration… `}`	InterfaceDeclaration	InterfaceDefinition, ClassOrInterface, TypeParameterized
`let` Identifier `=` Expr `;`	LetStmt	DeclStmt
`namespace` Identifier `{` Stmt… `}`	NamespaceDeclaration	NamespaceDefinition
`return` Expr `;`	ReturnStmt	JumpStmt
`switch` `(` Expr `) {` Case… `}`	SwitchStmt	ControlStmt
`throw` Expr `;`	ThrowStmt	JumpStmt
`try` `{` Stmt… `}` CatchClause… `finally` `{` Stmt… `}`	TryStmt	ControlStmt
`type` Identifier `=` TypeExpr `;`	TypeAliasDeclaration	TypeParameterized
`var` Identifier `=` Expr `;`	VarDeclStmt	DeclStmt
`while` `(` Expr `)` Stmt	WhileStmt	ControlStmt, LoopStmt
`with` `(` Expr `)` Stmt	WithStmt	ControlStmt
`{` Stmt… `}`	BlockStmt

Expression classes¶

There is a large number of expression classes, so we present them by category. All classes in this section are subclasses of Expr, except where noted otherwise.

Literals¶

All classes in this subsection are subclasses of Literal.

Expression syntax	CodeQL class
`true`	BooleanLiteral
`23`	NumberLiteral
`4.2`	NumberLiteral
`"Hello"`	StringLiteral
`/ab*c?/`	RegExpLiteral
`null`	NullLiteral

Identifiers¶

All identifiers are represented by the class Identifier, which has subclasses to represent specific kinds of identifiers:

VarAccess: an identifier that refers to a variable
VarDecl: an identifier that declares a variable, for example x in var x = "hi" or in function(x) { }
VarRef: a VarAccess or a VarDecl
Label: an identifier that refers to a statement label or a property, not a variable; in the following examples, l and p are labels:
- break l;
- l: for(;;) {}
- x.p
- { p: 42 }

Primary expressions¶

All classes in this subsection are subclasses of Expr.

Expression syntax	CodeQL class	Superclasses	Remarks
`this`	ThisExpr
`[` Expr… `]`	ArrayExpr
`{` Property… `}`	ObjectExpr
`function` `(` Parameter… `)` `{` Stmt… `}`	FunctionExpr	Function
`(` Parameter… `)` `=>` Expr	ArrowFunctionExpr	Function
`(` Expr `)`	ParExpr
` … `	TemplateLiteral		an element in a TemplateLiteral is either a TemplateElement representing a constant template element, or some other expression representing an interpolated expression of the form `${` Expr `}`
Expr ` … `	TaggedTemplateExpr		an element in a TaggedTemplateExpr is either a TemplateElement representing a constant template element, or some other expression representing an interpolated expression of the form `${` Expr `}`

Properties¶

All classes in this subsection are subclasses of Property. Note that Property is not a subclass of Expr.

Property syntax	CodeQL class	Superclasses
Identifier `:` Expr	ValueProperty
`get` Identifier `()` `{` Stmt… `}`	PropertyGetter	PropertyAccessor
`set` Identifier `(` Identifier `)` `{` Stmt… `}`	PropertySetter	PropertyAccessor

Property accesses¶

All classes in this subsection are subclasses of PropAccess.

Expression syntax	CodeQL class
Expr `.` Identifier	DotExpr
Expr `[` Expr `]`	IndexExpr

Function calls and `new`¶

All classes in this subsection are subclasses of InvokeExpr.

Expression syntax	CodeQL class	Remarks
Expr `(` Expr… `)`	CallExpr
Expr `.` Identifier `(` Expr… `)`	MethodCallExpr	this also includes calls of the form Expr `[` Expr `]` `(` Expr… `)`
`new` Expr `(` Expr… `)`	NewExpr

Unary expressions¶

All classes in this subsection are subclasses of UnaryExpr.

Expression syntax	CodeQL class
`~` Expr	BitNotExpr
`-` Expr	NegExpr
`+` Expr	PlusExpr
`!` Expr	LogNotExpr
`typeof` Expr	TypeofExpr
`void` Expr	VoidExpr
`delete` Expr	DeleteExpr
`...` Expr	SpreadElement

Binary expressions¶

All classes in this subsection are subclasses of BinaryExpr.

Expression syntax	CodeQL class	Superclasses
Expr `*` Expr	MulExpr
Expr `/` Expr	DivExpr
Expr `%` Expr	ModExpr
Expr `**` Expr	ExpExpr
Expr `+` Expr	AddExpr
Expr `-` Expr	SubExpr
Expr `<<` Expr	LShiftExpr
Expr `>>` Expr	RShiftExpr
Expr `>>>` Expr	URShiftExpr
Expr `&&` Expr	LogAndExpr
Expr `\|\|` Expr	LogOrExpr
Expr `<` Expr	LTExpr	Comparison
Expr `>` Expr	GTExpr	Comparison
Expr `<=` Expr	LEExpr	Comparison
Expr `>=` Expr	GEExpr	Comparison
Expr `==` Expr	EqExpr	EqualityTest, Comparison
Expr `!=` Expr	NEqExpr	EqualityTest, Comparison
Expr `===` Expr	StrictEqExpr	EqualityTest, Comparison
Expr `!==` Expr	StrictNEqExpr	EqualityTest, Comparison
Expr `&` Expr	BitAndExpr
Expr `\|` Expr	BitOrExpr
Expr `^` Expr	XOrExpr
Expr `in` Expr	InExpr
Expr `instanceof` Expr	InstanceofExpr

Assignment expressions¶

All classes in this table are subclasses of Assignment.

Expression syntax	CodeQL class	Superclasses
Expr `=` Expr	AssignExpr
Expr `+=` Expr	AssignAddExpr	CompoundAssignExpr
Expr `-=` Expr	AssignSubExpr	CompoundAssignExpr
Expr `*=` Expr	AssignMulExpr	CompoundAssignExpr
Expr `**=` Expr	AssignExpExpr	CompoundAssignExpr
Expr `/=` Expr	AssignDivExpr	CompoundAssignExpr
Expr `%=` Expr	AssignModExpr	CompoundAssignExpr
Expr `&=` Expr	AssignAndExpr	CompoundAssignExpr
Expr `\|=` Expr	AssignOrExpr	CompoundAssignExpr
Expr `^=` Expr	AssignXOrExpr	CompoundAssignExpr
Expr `<<=` Expr	AssignLShiftExpr	CompoundAssignExpr
Expr `>>=` Expr	AssignRShiftExpr	CompoundAssignExpr
Expr `>>>=` Expr	AssignURShiftExpr	CompoundAssignExpr

Update expressions¶

All classes in this table are subclasses of UpdateExpr.

Expression syntax	CodeQL class
Expr `++`	PostIncExpr
Expr `--`	PostDecExpr
`++` Expr	PreIncExpr
`--` Expr	PreDecExpr

Miscellaneous¶

All classes in this table are subclasses of Expr.

Expression syntax	CodeQL class
Expr `?` Expr `:` Expr	ConditionalExpr
Expr `,` … `,` Expr	SeqExpr
`await` Expr	AwaitExpr
`yield` Expr	YieldExpr