no-callback-literal.js
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/**
* Ensures that the callback pattern is followed properly
* with an Error object (or undefined or null) in the first position.
*/
'use strict'
// ------------------------------------------------------------------------------
// Helpers
// ------------------------------------------------------------------------------
/**
* Determine if a node has a possiblity to be an Error object
* @param {ASTNode} node ASTNode to check
* @returns {boolean} True if there is a chance it contains an Error obj
*/
function couldBeError (node) {
switch (node.type) {
case 'Identifier':
case 'CallExpression':
case 'NewExpression':
case 'MemberExpression':
case 'TaggedTemplateExpression':
case 'YieldExpression':
return true // possibly an error object.
case 'AssignmentExpression':
return couldBeError(node.right)
case 'SequenceExpression':
var exprs = node.expressions
return exprs.length !== 0 && couldBeError(exprs[exprs.length - 1])
case 'LogicalExpression':
return couldBeError(node.left) || couldBeError(node.right)
case 'ConditionalExpression':
return couldBeError(node.consequent) || couldBeError(node.alternate)
default:
return node.value === null
}
}
// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------
module.exports = {
meta: {
docs: {
url: 'https://github.com/xjamundx/eslint-plugin-standard#rules-explanations'
}
},
create: function (context) {
var callbackNames = context.options[0] || ['callback', 'cb']
function isCallback (name) {
return callbackNames.indexOf(name) > -1
}
return {
CallExpression: function (node) {
var errorArg = node.arguments[0]
var calleeName = node.callee.name
if (errorArg && !couldBeError(errorArg) && isCallback(calleeName)) {
context.report(node, 'Unexpected literal in error position of callback.')
}
}
}
}
}