76 lines
2.0 KiB
JavaScript
76 lines
2.0 KiB
JavaScript
/**
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* Ensures that the callback pattern is followed properly
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* with an Error object (or undefined or null) in the first position.
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*/
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'use strict'
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// ------------------------------------------------------------------------------
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// Helpers
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// ------------------------------------------------------------------------------
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/**
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* Determine if a node has a possiblity to be an Error object
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* @param {ASTNode} node ASTNode to check
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* @returns {boolean} True if there is a chance it contains an Error obj
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*/
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function couldBeError (node) {
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switch (node.type) {
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case 'Identifier':
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case 'CallExpression':
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case 'NewExpression':
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case 'MemberExpression':
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case 'TaggedTemplateExpression':
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case 'YieldExpression':
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return true // possibly an error object.
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case 'AssignmentExpression':
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return couldBeError(node.right)
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case 'SequenceExpression':
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var exprs = node.expressions
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return exprs.length !== 0 && couldBeError(exprs[exprs.length - 1])
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case 'LogicalExpression':
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return couldBeError(node.left) || couldBeError(node.right)
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case 'ConditionalExpression':
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return couldBeError(node.consequent) || couldBeError(node.alternate)
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default:
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return node.value === null
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}
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}
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// ------------------------------------------------------------------------------
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// Rule Definition
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// ------------------------------------------------------------------------------
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module.exports = {
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meta: {
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docs: {
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url: 'https://github.com/standard/eslint-plugin-standard#rules-explanations'
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}
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},
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create: function (context) {
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var callbackNames = context.options[0] || ['callback', 'cb']
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function isCallback (name) {
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return callbackNames.indexOf(name) > -1
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}
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return {
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CallExpression: function (node) {
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var errorArg = node.arguments[0]
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var calleeName = node.callee.name
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if (errorArg && !couldBeError(errorArg) && isCallback(calleeName)) {
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context.report(node, 'Unexpected literal in error position of callback.')
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}
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}
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}
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}
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}
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