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node_modules/eslint-plugin-standard/rules/no-callback-literal.js 2.05 KB
ce4c83ff   wxy   初始提交
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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.')
          }
        }
      }
    }
  }