ScopeManager

This document was written based on the implementation of eslint-scope, a fork of escope, and deprecates some members ESLint is not using.

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ScopeManager interface

ScopeManager object has all variable scopes.

Fields

scopes

• Type: Scope[]
• Description: All scopes.

globalScope

• Type: Scope
• Description: The root scope.

Methods

acquire(node, inner = false)

• Parameters:
  • node (ASTNode) ... An AST node to get their scope.
  • inner (boolean) ... If the node has multiple scope, this returns the outermost scope normally. If inner is true then this returns the innermost scope. Default is false.
• Return type: Scope | null
• Description: Get the scope of a given AST node. The gotten scope's block property is the node. This method never returns function-expression-name scope. If the node does not have their scope, this returns null.

addGlobals(names)

• Parameters:
  • names (string[]) ... Names of variables to add to the global scope.
• Return type: undefined
• Description: Adds variables to the global scope and resolves references to them. This method is used by the ESLint core and should never be used in rules.

getDeclaredVariables(node)

• Parameters:
  • node (ASTNode) ... An AST node to get their variables.
• Return type: Variable[]
• Description: Get the variables that a given AST node defines. The gotten variables' def[].node/def[].parent property is the node. If the node does not define any variable, this returns an empty array.

Deprecated members

Those members are defined but not used in ESLint.

isModule()

• Parameters:
• Return type: boolean
• Description: true if this program is module.

isImpliedStrict()

• Parameters:
• Return type: boolean
• Description: true if this program is strict mode implicitly. I.e., options.impliedStrict === true.

isStrictModeSupported()

• Parameters:
• Return type: boolean
• Description: true if this program supports strict mode. I.e., options.ecmaVersion >= 5.

acquireAll(node)

• Parameters:
  • node (ASTNode) ... An AST node to get their scope.
• Return type: Scope[] | null
• Description: Get the scopes of a given AST node. The gotten scopes' block property is the node. If the node does not have their scope, this returns null.

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Scope interface

Scope object has all variables and references in the scope.

Fields

type

• Type: string
• Description: The type of this scope. This is one of "block", "catch", "class", "class-field-initializer", "class-static-block", "for", "function", "function-expression-name", "global", "module", "switch", "with".

isStrict

• Type: boolean
• Description: true if this scope is strict mode.

upper

• Type: Scope | null
• Description: The parent scope. If this is the global scope then this property is null.

childScopes

• Type: Scope[]
• Description: The array of child scopes. This does not include grandchild scopes.

variableScope

• Type: Scope
• Description: The nearest ancestor whose type is one of "class-field-initializer", "class-static-block", "function", "global", or "module". For the aforementioned scopes this is a self-reference.

This represents the lowest enclosing function or top-level scope. Class field initializers and class static blocks are implicit functions. Historically, this was the scope which hosts variables that are defined by var declarations, and thus the name variableScope.

block

• Type: ASTNode
• Description: The AST node which created this scope.

variables

• Type: Variable[]
• Description: The array of all variables which are defined on this scope. This does not include variables which are defined in child scopes.

set

• Type: Map<string, Variable>
• Description: The map from variable names to variable objects.

references

• Type: Reference[]
• Description: The array of all references on this scope. This does not include references in child scopes.

through

• Type: Reference[]
• Description: The array of references which could not be resolved in this scope.

functionExpressionScope

• Type: boolean
• Description: true if this scope is "function-expression-name" scope.

implicit

This field exists only in the root Scope object (the global scope). It provides information about implicit global variables. Implicit global variables are variables that are neither built-in nor explicitly declared, but created implicitly by assigning values to undeclared variables in non-strict code. Variable objects for these variables are not present in the root Scope object's fields variables and set.

The value of the implicit field is an object with two properties.

variables

• Type: Variable[]
• Description: The array of all implicit global variables.

set

• Type: Map<string, Variable>
• Description: The map from variable names to variable objects for implicit global variables.

::: tip In Variable objects that represent implicit global variables, references is always an empty array. You can find references to these variables in the through field of the root Scope object (the global scope), among other unresolved references. :::

Deprecated members

Those members are defined but not used in ESLint.

taints

• Type: Map<string, boolean>
• Description: The map from variable names to tainted flag.

dynamic

• Type: boolean
• Description: true if this scope is dynamic. I.e., the type of this scope is "global" or "with".

directCallToEvalScope

• Type: boolean
• Description: true if this scope contains eval() invocations.

thisFound

• Type: boolean
• Description: true if this scope contains this.

resolve(node)

• Parameters:
  • node (ASTNode) ... An AST node to get their reference object. The type of the node must be "Identifier".
• Return type: Reference | null
• Description: Returns this.references.find(r => r.identifier === node).

isStatic()

• Parameters:
• Return type: boolean
• Description: Returns !this.dynamic.

isArgumentsMaterialized()

• Parameters:
• Return type: boolean
• Description: true if this is a "function" scope which has used arguments variable.

isThisMaterialized()

• Parameters:
• Return type: boolean
• Description: Returns this.thisFound.

isUsedName(name)

• Parameters:
  • name (string) ... The name to check.
• Return type: boolean
• Description: true if a given name is used in variable names or reference names.

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Variable interface

Variable object is variable's information.

Fields

name

• Type: string
• Description: The name of this variable.

scope

• Type: Scope
• Description: The scope in which this variable is defined.

identifiers

• Type: ASTNode[]
• Description: The array of Identifier nodes which define this variable. If this variable is redeclared, this array includes two or more nodes.

references

• Type: Reference[]
• Description: The array of the references of this variable.

defs

• Type: Definition[]
• Description: The array of the definitions of this variable.

Deprecated members

Those members are defined but not used in ESLint.

tainted

• Type: boolean
• Description: The tainted flag. (always false)

stack

• Type: boolean
• Description: The stack flag. (I'm not sure what this means.)

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Reference interface

Reference object is reference's information.

Fields

identifier

• Type: ASTNode
• Description: The Identifier or JSXIdentifier node of this reference.

from

• Type: Scope
• Description: The Scope object that this reference is on.

resolved

• Type: Variable | null
• Description: The Variable object that this reference refers. If such variable was not defined, this is null.

writeExpr

• Type: ASTNode | null
• Description: The ASTNode object which is right-hand side.

init

• Type: boolean
• Description: true if this writing reference is a variable initializer or a default value.

Methods

isWrite()

• Parameters:
• Return type: boolean
• Description: true if this reference is writing.

isRead()

• Parameters:
• Return type: boolean
• Description: true if this reference is reading.

isWriteOnly()

• Parameters:
• Return type: boolean
• Description: true if this reference is writing but not reading.

isReadOnly()

• Parameters:
• Return type: boolean
• Description: true if this reference is reading but not writing.

isReadWrite()

• Parameters:
• Return type: boolean
• Description: true if this reference is reading and writing.

Deprecated members

Those members are defined but not used in ESLint.

tainted

• Type: boolean
• Description: The tainted flag. (always false)

flag

• Type: number
• Description: 1 is reading, 2 is writing, 3 is reading/writing.

partial

• Type: boolean
• Description: The partial flag.

isStatic()

• Parameters:
• Return type: boolean
• Description: true if this reference is resolved statically.

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Definition interface

Definition object is variable definition's information.

Fields

type

• Type: string
• Description: The type of this definition. One of "CatchClause", "ClassName", "FunctionName", "ImplicitGlobalVariable", "ImportBinding", "Parameter", and "Variable".

name

• Type: ASTNode
• Description: The Identifier node of this definition.

node

• Type: ASTNode
• Description: The enclosing node of the name.

type	node
"CatchClause"	CatchClause
"ClassName"	ClassDeclaration or ClassExpression
"FunctionName"	FunctionDeclaration or FunctionExpression
"ImplicitGlobalVariable"	AssignmentExpression or ForInStatement or ForOfStatement
"ImportBinding"	ImportSpecifier, ImportDefaultSpecifier, or ImportNamespaceSpecifier
"Parameter"	FunctionDeclaration, FunctionExpression, or ArrowFunctionExpression
"Variable"	VariableDeclarator

parent

• Type: ASTNode | undefined | null
• Description: The enclosing statement node of the name.

type	parent
"CatchClause"	null
"ClassName"	null
"FunctionName"	null
"ImplicitGlobalVariable"	null
"ImportBinding"	ImportDeclaration
"Parameter"	null
"Variable"	VariableDeclaration

Deprecated members

Those members are defined but not used in ESLint.

index

• Type: number | undefined | null
• Description: The index in the declaration statement.

kind

• Type: string | undefined | null
• Description: The kind of the declaration statement.