/
no-promise-executor-return.js
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no-promise-executor-return.js
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/**
* @fileoverview Rule to disallow returning values from Promise executor functions
* @author Milos Djermanovic
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const { findVariable } = require("eslint-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const functionTypesToCheck = new Set(["ArrowFunctionExpression", "FunctionExpression"]);
/**
* Determines whether the given identifier node is a reference to a global variable.
* @param {ASTNode} node `Identifier` node to check.
* @param {Scope} scope Scope to which the node belongs.
* @returns {boolean} True if the identifier is a reference to a global variable.
*/
function isGlobalReference(node, scope) {
const variable = findVariable(scope, node);
return variable !== null && variable.scope.type === "global" && variable.defs.length === 0;
}
/**
* Finds function's outer scope.
* @param {Scope} scope Function's own scope.
* @returns {Scope} Function's outer scope.
*/
function getOuterScope(scope) {
const upper = scope.upper;
if (upper.type === "function-expression-name") {
return upper.upper;
}
return upper;
}
/**
* Determines whether the given function node is used as a Promise executor.
* @param {ASTNode} node The node to check.
* @param {Scope} scope Function's own scope.
* @returns {boolean} `true` if the node is a Promise executor.
*/
function isPromiseExecutor(node, scope) {
const parent = node.parent;
return parent.type === "NewExpression" &&
parent.arguments[0] === node &&
parent.callee.type === "Identifier" &&
parent.callee.name === "Promise" &&
isGlobalReference(parent.callee, getOuterScope(scope));
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "problem",
docs: {
description: "disallow returning values from Promise executor functions",
category: "Possible Errors",
recommended: false,
url: "https://eslint.org/docs/rules/no-promise-executor-return"
},
schema: [],
messages: {
returnsValue: "Return values from promise executor functions cannot be read."
}
},
create(context) {
let funcInfo = null;
/**
* Reports the given node.
* @param {ASTNode} node Node to report.
* @returns {void}
*/
function report(node) {
context.report({ node, messageId: "returnsValue" });
}
return {
onCodePathStart(_, node) {
funcInfo = {
upper: funcInfo,
shouldCheck: functionTypesToCheck.has(node.type) && isPromiseExecutor(node, context.getScope())
};
if (funcInfo.shouldCheck && node.type === "ArrowFunctionExpression" && node.expression) {
report(node.body);
}
},
onCodePathEnd() {
funcInfo = funcInfo.upper;
},
ReturnStatement(node) {
if (funcInfo.shouldCheck && node.argument) {
report(node);
}
}
};
}
};