eslint/lib/rules/newline-per-chained-call.js

   1 /**
   2  * @fileoverview Rule to ensure newline per method call when chaining calls
   3  * @author Rajendra Patil
   4  * @author Burak Yigit Kaya
   5  */
   6
   7 "use strict";
   8
   9 const astUtils = require("./utils/ast-utils");
  10
  11 //------------------------------------------------------------------------------
  12 // Rule Definition
  13 //------------------------------------------------------------------------------
  14
  15 module.exports = {
  16     meta: {
  17         type: "layout",
  18
  19         docs: {
  20             description: "require a newline after each call in a method chain",
  21             recommended: false,
  22             url: "https://eslint.org/docs/rules/newline-per-chained-call"
  23         },
  24
  25         fixable: "whitespace",
  26
  27         schema: [{
  28             type: "object",
  29             properties: {
  30                 ignoreChainWithDepth: {
  31                     type: "integer",
  32                     minimum: 1,
  33                     maximum: 10,
  34                     default: 2
  35                 }
  36             },
  37             additionalProperties: false
  38         }],
  39         messages: {
  40             expected: "Expected line break before `{{callee}}`."
  41         }
  42     },
  43
  44     create(context) {
  45
  46         const options = context.options[0] || {},
  47             ignoreChainWithDepth = options.ignoreChainWithDepth || 2;
  48
  49         const sourceCode = context.getSourceCode();
  50
  51         /**
  52          * Get the prefix of a given MemberExpression node.
  53          * If the MemberExpression node is a computed value it returns a
  54          * left bracket. If not it returns a period.
  55          * @param {ASTNode} node A MemberExpression node to get
  56          * @returns {string} The prefix of the node.
  57          */
  58         function getPrefix(node) {
  59             if (node.computed) {
  60                 if (node.optional) {
  61                     return "?.[";
  62                 }
  63                 return "[";
  64             }
  65             if (node.optional) {
  66                 return "?.";
  67             }
  68             return ".";
  69         }
  70
  71         /**
  72          * Gets the property text of a given MemberExpression node.
  73          * If the text is multiline, this returns only the first line.
  74          * @param {ASTNode} node A MemberExpression node to get.
  75          * @returns {string} The property text of the node.
  76          */
  77         function getPropertyText(node) {
  78             const prefix = getPrefix(node);
  79             const lines = sourceCode.getText(node.property).split(astUtils.LINEBREAK_MATCHER);
  80             const suffix = node.computed && lines.length === 1 ? "]" : "";
  81
  82             return prefix + lines[0] + suffix;
  83         }
  84
  85         return {
  86             "CallExpression:exit"(node) {
  87                 const callee = astUtils.skipChainExpression(node.callee);
  88
  89                 if (callee.type !== "MemberExpression") {
  90                     return;
  91                 }
  92
  93                 let parent = astUtils.skipChainExpression(callee.object);
  94                 let depth = 1;
  95
  96                 while (parent && parent.callee) {
  97                     depth += 1;
  98                     parent = astUtils.skipChainExpression(astUtils.skipChainExpression(parent.callee).object);
  99                 }
 100
 101                 if (depth > ignoreChainWithDepth && astUtils.isTokenOnSameLine(callee.object, callee.property)) {
 102                     const firstTokenAfterObject = sourceCode.getTokenAfter(callee.object, astUtils.isNotClosingParenToken);
 103
 104                     context.report({
 105                         node: callee.property,
 106                         loc: {
 107                             start: firstTokenAfterObject.loc.start,
 108                             end: callee.loc.end
 109                         },
 110                         messageId: "expected",
 111                         data: {
 112                             callee: getPropertyText(callee)
 113                         },
 114                         fix(fixer) {
 115                             return fixer.insertTextBefore(firstTokenAfterObject, "\n");
 116                         }
 117                     });
 118                 }
 119             }
 120         };
 121     }
 122 };