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/**
* @fileoverview Rule to check for "block scoped" variables by binding context
* @author Matt DuVall <http://www.mattduvall.com>
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "enforce the use of variables within the scope they are defined",
category: "Best Practices",
recommended: false,
url: "https://eslint.org/docs/rules/block-scoped-var"
},
schema: [],
messages: {
outOfScope: "'{{name}}' used outside of binding context."
}
},
create(context) {
let stack = [];
/**
* Makes a block scope.
* @param {ASTNode} node A node of a scope.
* @returns {void}
*/
function enterScope(node) {
stack.push(node.range);
}
/**
* Pops the last block scope.
* @returns {void}
*/
function exitScope() {
stack.pop();
}
/**
* Reports a given reference.
* @param {eslint-scope.Reference} reference A reference to report.
* @returns {void}
*/
function report(reference) {
const identifier = reference.identifier;
context.report({ node: identifier, messageId: "outOfScope", data: { name: identifier.name } });
}
/**
* Finds and reports references which are outside of valid scopes.
* @param {ASTNode} node A node to get variables.
* @returns {void}
*/
function checkForVariables(node) {
if (node.kind !== "var") {
return;
}
// Defines a predicate to check whether or not a given reference is outside of valid scope.
const scopeRange = stack[stack.length - 1];
/**
* Check if a reference is out of scope
* @param {ASTNode} reference node to examine
* @returns {boolean} True is its outside the scope
* @private
*/
function isOutsideOfScope(reference) {
const idRange = reference.identifier.range;
return idRange[0] < scopeRange[0] || idRange[1] > scopeRange[1];
}
// Gets declared variables, and checks its references.
const variables = context.getDeclaredVariables(node);
for (let i = 0; i < variables.length; ++i) {
// Reports.
variables[i]
.references
.filter(isOutsideOfScope)
.forEach(report);
}
}
return {
Program(node) {
stack = [node.range];
},
// Manages scopes.
BlockStatement: enterScope,
"BlockStatement:exit": exitScope,
ForStatement: enterScope,
"ForStatement:exit": exitScope,
ForInStatement: enterScope,
"ForInStatement:exit": exitScope,
ForOfStatement: enterScope,
"ForOfStatement:exit": exitScope,
SwitchStatement: enterScope,
"SwitchStatement:exit": exitScope,
CatchClause: enterScope,
"CatchClause:exit": exitScope,
// Finds and reports references which are outside of valid scope.
VariableDeclaration: checkForVariables
};
}
};
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