A list of all babels types with an explanation, and a link to astexplorer with an example

babelTypeDescriptions.md

The goal is to have a link to ASTexplorer to demonstrate what each type is. Types have been broken into sections if they are not core parts of javascript (JSX, type annotations, typescript types), however are otherwise in alphabetical order.

WIP - un-added types have a leading ^^^^ while I am working on them.

Important Base Parts

Knowing these will help everywhere

• identifier A named property, such as a declared variable or object property.
• blockStatement Anything to be run as part of resolving an expression. (Effectively anything that would go between {} brackets, whether that is in a for statement, or function expression. It will be found as the body property of the expression.
• file identifies that all code within the AST down from this comes from a single javascript file within the filesystem.
• program The body type of a file, under which the rest of the file's AST sits. (files may also have comments and tokens)
• expressionStatement func()
• variableDeclaration var a = 'a';
• variableDeclarator var a = 'a';

Literal types

Literal types are javascript primitives. They are normally simple values.

• booleanLiteral true or false
• directiveLiteral "use strict"
• nullLiteral null
• numericLiteral Any number
• regExpLiteral /asdf/
• stringLiteral 'this kind of thing' or "this kind of thing"
• templateLiteral `something like this`

Expressions

Expressions can be seen as taking an action, whether adding a new

• arrayExpression ['a']
• arrowFunctionExpression () => {}
• assignmentExpression a = 1 + 2 Assignment outside of an initial instantiation (reassigning a variable, or object property)
• awaitExpression await func()
• binaryExpression An operation with two sides, such as base mathematical operations or concatenation
• bindExpression let a = ::b.c
• callExpression func()
• classExpression var foo = class {}
• conditionalExpression a ? b : c
• doExpression let a = do {}
• functionExpression var x = function() {}
• logicalExpression a || b or a && b
• memberExpression a.b()
• newExpression new a
• objectExpression const a = {}
• ^^^^parenthesizedExpression
• sequenceExpression (1, 2, 3)
• taggedTemplateExpression func`a`
• thisExpression this
• unaryExpression Operators with a single argument; typeof or delete
• updateExpression ++a
• yieldExpression function* a () { yield b }

(possible other bits)

Declarations (declarators?)

Statements

Patterns

Javascript Properties

• arrayPattern function a ([ b, c ]) {}
• assignmentPattern function a (b = 1) {}
• breakStatement while (true) { break }
• catchClause try {} catch (e) {}
• classBody The body of a classDeclaration
• classDeclaration class a {}
• classImplements class a implements b {}
• classMethod class b { constructor() {} } the constructor is an example of a class method
• classProperty Assigned property within a class
• continueStatement while (true) { continue }
• debuggerStatement debugger
• decorator
• directive "use strict"
• doWhileStatement do {} while (true)
• ^^^^emptyStatement
• exportAllDeclaration export * from './place';
• exportDefaultDeclaration export default a
• ^^^^exportDefaultSpecifier
• exportNamedDeclaration export { a }
• ^^^^exportNamespaceSpecifier
• exportSpecifier export { a as b }
• forInStatement for (let a in b) { /* do something over an object's properties */ }
• forOfStatement for (let a of b) { /* do something over an array's items */ }
• forStatement for (var i = 0; i < val; i++) {}
• functionDeclaration function a () {}
• ifStatement if (true) {}
• ^^^^import
• importDeclaration import a from 'a'
• importDefaultSpecifier import a from 'a'
• importNamespaceSpecifier import * as a from 'a'
• importSpecifier import { a } from 'a'
• ^^^^inferredPredicate
• ^^^^interfaceDeclaration
• ^^^^interfaceExtends
• ^^^^labeledStatement
• ^^^^metaProperty
• ^^^^noop
• objectMethod let a = { a () {} }
• objectPattern function a ({ b }) {}
• objectProperty Any value added to an object.
• restElement function a (...a) {}
• returnStatement () => { return }
• spreadElement let a = [...b]
• super class a extends b { constructor () { super() } }
• switchCase case a: // the case results
• switchStatement the whole switch statement beginning with switch (a) {
• templateElement ab
• throwStatement throw a
• tryStatement try {} catch (e) {} or try {} finally {}
• whileStatement while (true) {}
• withStatement mdn recommends don't use with statements.

JSX Properties

These are parts of JSX syntax. For more information on JSX, please see the react documentation.

• jSXAttribute <B c="c" />
• jSXClosingElement <div>a</div>
• jSXClosingFragment <></>
• jSXElement <div>a</div>
• jSXEmptyExpression <B>{}</B>
• jSXExpressionContainer <B c={c} />
• jSXFragment <></>
• jSXIdentifier <B />
• ^^^^jSXMemberExpression
• ^^^^jSXNamespacedName
• jSXOpeningElement <div>a</div>
• jSXOpeningFragment <></>
• jSXSpreadAttribute <B {...c} />
• jSXSpreadChild <B>{...c}</B>
• jSXText <div>a</div>

Other Types Bits

Type types

These properties are used for typing systems, mostly flow.

• typeCastExpression func(a: string)
• functionTypeParam type a = (b: string) => mixed
• opaqueType opaque type a = string;
• ^^^^qualifiedTypeIdentifier
• typeAlias type a = string
• typeAnnotation let a: string = 'a'
• ^^^^typeParameter
• ^^^^typeParameterDeclaration
• typeParameterInstantiation type a = A<*>
• ^^^^objectTypeCallProperty
• ^^^^objectTypeIndexer
• objectTypeProperty type a = { b: string }
• objectTypeSpreadProperty type a = { ...string }

Declarations

• declareClass declare class a {}
• ^^^^declareExportAllDeclaration
• declareExportDeclaration declare export default boolean
• declareFunction declare function a(b: number): string;
• ^^^^declareInterface
• declareModule declare module 'a' {}
• ^^^^declareModuleExports declare module.exports: 'a';
• ^^^^declareOpaqueType
• declareTypeAlias declare type a = boolean
• declareVariable declare var a: boolean
• ^^^^declaredPredicate

Type Annotations (most likely flow)

These type annotations are the kind used in flow. I recommend reading the flow documentation to understand these types. Each will be found within a typeAnnotation property for an identifier.

• anyTypeAnnotation type a = any;
• arrayTypeAnnotation type a = number[]
• booleanLiteralTypeAnnotation type a = true
• booleanTypeAnnotation type a= boolean
• ^^^^emptyTypeAnnotation
• existsTypeAnnotation type a = *
• functionTypeAnnotation type a = () => {}
• genericTypeAnnotation type a = b
• intersectionTypeAnnotation type a = string & 'a'
• mixedTypeAnnotation type a = mixed
• nullLiteralTypeAnnotation type a = null
• nullableTypeAnnotation type a = ?string
• numberLiteralTypeAnnotation type a = 5
• numberTypeAnnotation type a = number
• objectTypeAnnotation type a = {}
• stringLiteralTypeAnnotation type a = 'a'
• stringTypeAnnotation type a = string
• thisTypeAnnotation type a = this
• tupleTypeAnnotation type a = [b, c]
• typeofTypeAnnotation type a = typeof b
• unionTypeAnnotation type a = string | number
• voidTypeAnnotation type a = void

Typescript Types

• ^^^^tSAnyKeyword
• ^^^^tSArrayType
• ^^^^tSAsExpression
• ^^^^tSBooleanKeyword
• ^^^^tSCallSignatureDeclaration
• ^^^^tSConstructSignatureDeclaration
• ^^^^tSConstructorType
• ^^^^tSDeclareFunction
• ^^^^tSDeclareMethod
• ^^^^tSEnumDeclaration
• ^^^^tSEnumMember
• ^^^^tSExportAssignment
• ^^^^tSExpressionWithTypeArguments
• ^^^^tSExternalModuleReference
• ^^^^tSFunctionType
• ^^^^tSImportEqualsDeclaration
• ^^^^tSIndexSignature
• ^^^^tSIndexedAccessType
• ^^^^tSInterfaceBody
• ^^^^tSInterfaceDeclaration
• ^^^^tSIntersectionType
• ^^^^tSLiteralType
• ^^^^tSMappedType
• ^^^^tSMethodSignature
• ^^^^tSModuleBlock
• ^^^^tSModuleDeclaration
• ^^^^tSNamespaceExportDeclaration
• ^^^^tSNeverKeyword
• ^^^^tSNonNullExpression
• ^^^^tSNullKeyword
• ^^^^tSNumberKeyword
• ^^^^tSObjectKeyword
• ^^^^tSParameterProperty
• ^^^^tSParenthesizedType
• ^^^^tSPropertySignature
• ^^^^tSQualifiedName
• ^^^^tSStringKeyword
• ^^^^tSSymbolKeyword
• ^^^^tSThisType
• ^^^^tSTupleType
• ^^^^tSTypeAliasDeclaration
• ^^^^tSTypeAnnotation
• ^^^^tSTypeAssertion
• ^^^^tSTypeLiteral
• ^^^^tSTypeOperator
• ^^^^tSTypeParameter
• ^^^^tSTypeParameterDeclaration
• ^^^^tSTypeParameterInstantiation
• ^^^^tSTypePredicate
• ^^^^tSTypeQuery
• ^^^^tSTypeReference
• ^^^^tSUndefinedKeyword
• ^^^^tSUnionType
• ^^^^tSVoidKeyword