Statements and Declarations

A statement can be one of the following:

type Statement = BlockStatement | BreakStatement | ContinueStatement |
    DebuggerStatement | DoWhileStatement | EmptyStatement |
    ExpressionStatement | ForStatement | ForInStatement |
    ForOfStatement | FunctionDeclaration | IfStatement |
    LabeledStatement | ReturnStatement | SwitchStatement |
    ThrowStatement | TryStatement | VariableDeclaration |
    WhileStatement | WithStatement;

A declaration can be one of the following:

type Declaration = ClassDeclaration | FunctionDeclaration |  VariableDeclaration;

A statement list item is either a statement or a declaration:

type StatementListItem = Declaration | Statement;

Block Statement

A series of statements enclosed by a pair of curly braces form a block statement:

interface BlockStatement {
    type: 'BlockStatement';
    body: StatementListItem[];
}

Break Statement

interface BreakStatement {
    type: 'BreakStatement';
    label: Identifier | null;
}

Class Declaration

interface ClassDeclaration {
    type: 'ClassDeclaration';
    id: Identifier | null;
    superClass: Identifier | null;
    body: ClassBody;
}

Continue Statement

interface ContinueStatement {
    type: 'ContinueStatement';
    label: Identifier | null;
}

Debugger Statement

interface DebuggerStatement {
    type: 'DebuggerStatement';
}

Do-While Statement

interface DoWhileStatement {
    type: 'DoWhileStatement';
    body: Statement;
    test: Expression;
}

Empty Statement

interface EmptyStatement {
    type: 'EmptyStatement';
}

Expression Statement

interface ExpressionStatement {
    type: 'ExpressionStatement';
    expression: Expression;
    directive?: string;
}

When the expression statement represents a directive (such as "use strict"), then the directive property will contain the directive string.

For Statement

interface ForStatement {
    type: 'ForStatement';
    init: Expression | VariableDeclaration | null;
    test: Expression | null;
    update: Expression | null;
    body: Statement;
}

For-In Statement

interface ForInStatement {
    type: 'ForInStatement';
    left: Expression;
    right: Expression;
    body: Statement;
    each: false;
}

For-Of Statement

interface ForOfStatement {
    type: 'ForOfStatement';
    left: Expression;
    right: Expression;
    body: Statement;
}

Function Declaration

interface FunctionDeclaration {
    type: 'FunctionDeclaration';
    id: Identifier | null;
    params: FunctionParameter[];
    body: BlockStatement;
    generator: boolean;
    async: boolean;
    expression: false;
}

with

type FunctionParameter = AssignmentPattern | Identifier | BindingPattern;

If Statement

interface IfStatement {
    type: 'IfStatement';
    test: Expression;
    consequent: Statement;
    alternate?: Statement;
}

Labelled Statement

A statement prefixed by a label becomes a labelled statement:

interface LabeledStatement {
    type: 'LabeledStatement';
    label: Identifier;
    body: Statement;
}

Return Statement

interface ReturnStatement {
    type: 'ReturnStatement';
    argument: Expression | null;
}

Switch Statement

interface SwitchStatement {
    type: 'SwitchStatement';
    discriminant: Expression;
    cases: SwitchCase[];
}

with

interface SwitchCase {
    type: 'SwitchCase';
    test: Expression | null;
    consequent: Statement[];
}

Throw Statement

interface ThrowStatement {
    type: 'ThrowStatement';
    argument: Expression;
}

Try Statement

interface TryStatement {
    type: 'TryStatement';
    block: BlockStatement;
    handler: CatchClause | null;
    finalizer: BlockStatement | null;
}

with

interface CatchClause {
    type: 'CatchClause';
    param: Identifier | BindingPattern;
    body: BlockStatement;
}

Variable Declaration

interface VariableDeclaration {
    type: 'VariableDeclaration';
    declarations: VariableDeclarator[];
    kind: 'var' | 'const' | 'let';
}

with

interface VariableDeclarator {
    type: 'VariableDeclarator';
    id: Identifier | BindingPattern;
    init: Expression | null;
}

While Statement

interface WhileStatement {
    type: 'WhileStatement';
    test: Expression;
    body: Statement;
}

With Statement

interface WithStatement {
    type: 'WithStatement';
    object: Expression;
    body: Statement;
}