• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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
9const astUtils = require("./utils/ast-utils");
10
11//------------------------------------------------------------------------------
12// Rule Definition
13//------------------------------------------------------------------------------
14
15module.exports = {
16    meta: {
17        type: "layout",
18
19        docs: {
20            description: "require a newline after each call in a method chain",
21            category: "Stylistic Issues",
22            recommended: false,
23            url: "https://eslint.org/docs/rules/newline-per-chained-call"
24        },
25
26        fixable: "whitespace",
27
28        schema: [{
29            type: "object",
30            properties: {
31                ignoreChainWithDepth: {
32                    type: "integer",
33                    minimum: 1,
34                    maximum: 10,
35                    default: 2
36                }
37            },
38            additionalProperties: false
39        }],
40        messages: {
41            expected: "Expected line break before `{{callee}}`."
42        }
43    },
44
45    create(context) {
46
47        const options = context.options[0] || {},
48            ignoreChainWithDepth = options.ignoreChainWithDepth || 2;
49
50        const sourceCode = context.getSourceCode();
51
52        /**
53         * Get the prefix of a given MemberExpression node.
54         * If the MemberExpression node is a computed value it returns a
55         * left bracket. If not it returns a period.
56         * @param  {ASTNode} node A MemberExpression node to get
57         * @returns {string} The prefix of the node.
58         */
59        function getPrefix(node) {
60            if (node.computed) {
61                if (node.optional) {
62                    return "?.[";
63                }
64                return "[";
65            }
66            if (node.optional) {
67                return "?.";
68            }
69            return ".";
70        }
71
72        /**
73         * Gets the property text of a given MemberExpression node.
74         * If the text is multiline, this returns only the first line.
75         * @param {ASTNode} node A MemberExpression node to get.
76         * @returns {string} The property text of the node.
77         */
78        function getPropertyText(node) {
79            const prefix = getPrefix(node);
80            const lines = sourceCode.getText(node.property).split(astUtils.LINEBREAK_MATCHER);
81            const suffix = node.computed && lines.length === 1 ? "]" : "";
82
83            return prefix + lines[0] + suffix;
84        }
85
86        return {
87            "CallExpression:exit"(node) {
88                const callee = astUtils.skipChainExpression(node.callee);
89
90                if (callee.type !== "MemberExpression") {
91                    return;
92                }
93
94                let parent = astUtils.skipChainExpression(callee.object);
95                let depth = 1;
96
97                while (parent && parent.callee) {
98                    depth += 1;
99                    parent = astUtils.skipChainExpression(astUtils.skipChainExpression(parent.callee).object);
100                }
101
102                if (depth > ignoreChainWithDepth && astUtils.isTokenOnSameLine(callee.object, callee.property)) {
103                    const firstTokenAfterObject = sourceCode.getTokenAfter(callee.object, astUtils.isNotClosingParenToken);
104
105                    context.report({
106                        node: callee.property,
107                        loc: {
108                            start: firstTokenAfterObject.loc.start,
109                            end: callee.loc.end
110                        },
111                        messageId: "expected",
112                        data: {
113                            callee: getPropertyText(callee)
114                        },
115                        fix(fixer) {
116                            return fixer.insertTextBefore(firstTokenAfterObject, "\n");
117                        }
118                    });
119                }
120            }
121        };
122    }
123};
124