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/**
* @fileoverview Ensure handling of errors when we know they exist.
* @author Jamund Ferguson
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "require error handling in callbacks",
category: "Node.js and CommonJS",
recommended: false,
url: "https://eslint.org/docs/rules/handle-callback-err"
},
schema: [
{
type: "string"
}
],
messages: {
expected: "Expected error to be handled."
}
},
create(context) {
const errorArgument = context.options[0] || "err";
/**
* Checks if the given argument should be interpreted as a regexp pattern.
* @param {string} stringToCheck The string which should be checked.
* @returns {boolean} Whether or not the string should be interpreted as a pattern.
*/
function isPattern(stringToCheck) {
const firstChar = stringToCheck[0];
return firstChar === "^";
}
/**
* Checks if the given name matches the configured error argument.
* @param {string} name The name which should be compared.
* @returns {boolean} Whether or not the given name matches the configured error variable name.
*/
function matchesConfiguredErrorName(name) {
if (isPattern(errorArgument)) {
const regexp = new RegExp(errorArgument);
return regexp.test(name);
}
return name === errorArgument;
}
/**
* Get the parameters of a given function scope.
* @param {Object} scope The function scope.
* @returns {Array} All parameters of the given scope.
*/
function getParameters(scope) {
return scope.variables.filter(variable => variable.defs[0] && variable.defs[0].type === "Parameter");
}
/**
* Check to see if we're handling the error object properly.
* @param {ASTNode} node The AST node to check.
* @returns {void}
*/
function checkForError(node) {
const scope = context.getScope(),
parameters = getParameters(scope),
firstParameter = parameters[0];
if (firstParameter && matchesConfiguredErrorName(firstParameter.name)) {
if (firstParameter.references.length === 0) {
context.report({ node, messageId: "expected" });
}
}
}
return {
FunctionDeclaration: checkForError,
FunctionExpression: checkForError,
ArrowFunctionExpression: checkForError
};
}
};
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