This document specifies the extensions to the core ESTree AST types to support the ES6 grammar.
extend interface Program {
sourceType: "script" | "module";
body: [ Statement | ModuleDeclaration ];
}Parsers must specify sourceType as "module" if the source has been parsed as an ES6 module. Otherwise, sourceType must be "script".
extend interface Function {
generator: boolean;
}interface ForOfStatement <: ForInStatement {
type: "ForOfStatement";
}extend interface VariableDeclaration {
kind: "var" | "let" | "const";
}interface Super <: Node {
type: "Super";
}
extend interface CallExpression {
callee: Expression | Super;
}
extend interface MemberExpression {
object: Expression | Super;
}A super pseudo-expression.
interface SpreadElement <: Node {
type: "SpreadElement";
argument: Expression;
}
extend interface ArrayExpression {
elements: [ Expression | SpreadElement | null ];
}
extend interface CallExpression {
arguments: [ Expression | SpreadElement ];
}Spread expression, e.g., [head, ...iter, tail], f(head, ...iter, ...tail).
FIXME: This describes the Esprima and Acorn behaviors, which is not currently aligned with the SpiderMonkey behavior.
extend interface AssignmentExpression {
left: Pattern;
}Note that pre-ES6 code was allowed to pass references around and so left was much more liberal; an implementation might choose to continue using old definition if it needs to support such legacy code.
extend interface Property {
key: Expression;
method: boolean;
shorthand: boolean;
computed: boolean;
}interface ArrowFunctionExpression <: Function, Expression {
type: "ArrowFunctionExpression";
body: BlockStatement | Expression;
expression: boolean;
}A fat arrow function expression, e.g., let foo = (bar) => { /* body */ }.
interface YieldExpression <: Expression {
type: "YieldExpression";
argument: Expression | null;
delegate: boolean;
}A yield expression.
interface TemplateLiteral <: Expression {
type: "TemplateLiteral";
quasis: [ TemplateElement ];
expressions: [ Expression ];
}interface TaggedTemplateExpression <: Expression {
type: "TaggedTemplateExpression";
tag: Expression;
quasi: TemplateLiteral;
}interface TemplateElement <: Node {
type: "TemplateElement";
tail: boolean;
value: {
cooked: string;
raw: string;
};
}interface AssignmentProperty <: Property {
type: "Property"; // inherited
value: Pattern;
kind: "init";
method: false;
}
interface ObjectPattern <: Pattern {
type: "ObjectPattern";
properties: [ AssignmentProperty ];
}interface ArrayPattern <: Pattern {
type: "ArrayPattern";
elements: [ Pattern | null ];
}interface RestElement <: Pattern {
type: "RestElement";
argument: Pattern;
}interface AssignmentPattern <: Pattern {
type: "AssignmentPattern";
left: Pattern;
right: Expression;
}interface Class <: Node {
id: Identifier | null;
superClass: Expression | null;
body: ClassBody;
}interface ClassBody <: Node {
type: "ClassBody";
body: [ MethodDefinition ];
}interface MethodDefinition <: Node {
type: "MethodDefinition";
key: Expression;
value: FunctionExpression;
kind: "constructor" | "method" | "get" | "set";
computed: boolean;
static: boolean;
}interface ClassDeclaration <: Class, Declaration {
type: "ClassDeclaration";
id: Identifier;
}interface ClassExpression <: Class, Expression {
type: "ClassExpression";
}interface MetaProperty <: Expression {
type: "MetaProperty";
meta: Identifier;
property: Identifier;
}interface ModuleDeclaration <: Node { }A module import or export declaration.
interface ModuleSpecifier <: Node {
local: Identifier;
}A specifier in an import or export declaration.
interface ImportDeclaration <: ModuleDeclaration {
type: "ImportDeclaration";
specifiers: [ ImportSpecifier | ImportDefaultSpecifier | ImportNamespaceSpecifier ];
source: Literal;
}An import declaration, e.g., import foo from "mod";.
interface ImportSpecifier <: ModuleSpecifier {
type: "ImportSpecifier";
imported: Identifier;
}An imported variable binding, e.g., {foo} in import {foo} from "mod" or {foo as bar} in import {foo as bar} from "mod". The imported field refers to the name of the export imported from the module. The local field refers to the binding imported into the local module scope. If it is a basic named import, such as in import {foo} from "mod", both imported and local are equivalent Identifier nodes; in this case an Identifier node representing foo. If it is an aliased import, such as in import {foo as bar} from "mod", the imported field is an Identifier node representing foo, and the local field is an Identifier node representing bar.
interface ImportDefaultSpecifier <: ModuleSpecifier {
type: "ImportDefaultSpecifier";
}A default import specifier, e.g., foo in import foo from "mod.js".
interface ImportNamespaceSpecifier <: ModuleSpecifier {
type: "ImportNamespaceSpecifier";
}A namespace import specifier, e.g., * as foo in import * as foo from "mod.js".
interface ExportNamedDeclaration <: ModuleDeclaration {
type: "ExportNamedDeclaration";
declaration: Declaration | null;
specifiers: [ ExportSpecifier ];
source: Literal | null;
}An export named declaration, e.g., export {foo, bar};, export {foo} from "mod"; or export var foo = 1;.
Note: Having declaration populated with non-empty specifiers or non-null source results in an invalid state.
interface ExportSpecifier <: ModuleSpecifier {
type: "ExportSpecifier";
exported: Identifier;
}An exported variable binding, e.g., {foo} in export {foo} or {bar as foo} in export {bar as foo}. The exported field refers to the name exported in the module. The local field refers to the binding into the local module scope. If it is a basic named export, such as in export {foo}, both exported and local are equivalent Identifier nodes; in this case an Identifier node representing foo. If it is an aliased export, such as in export {bar as foo}, the exported field is an Identifier node representing foo, and the local field is an Identifier node representing bar.
interface ExportDefaultDeclaration <: ModuleDeclaration {
type: "ExportDefaultDeclaration";
declaration: Declaration | Expression;
}An export default declaration, e.g., export default function () {}; or export default 1;.
interface ExportAllDeclaration <: ModuleDeclaration {
type: "ExportAllDeclaration";
source: Literal;
}An export batch declaration, e.g., export * from "mod";.