--- /dev/null
+/**
+ * @fileoverview Rule to ensure newline per method call when chaining calls
+ * @author Rajendra Patil
+ * @author Burak Yigit Kaya
+ */
+
+"use strict";
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "layout",
+
+ docs: {
+ description: "require a newline after each call in a method chain",
+ category: "Stylistic Issues",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/newline-per-chained-call"
+ },
+
+ fixable: "whitespace",
+
+ schema: [{
+ type: "object",
+ properties: {
+ ignoreChainWithDepth: {
+ type: "integer",
+ minimum: 1,
+ maximum: 10,
+ default: 2
+ }
+ },
+ additionalProperties: false
+ }],
+ messages: {
+ expected: "Expected line break before `{{callee}}`."
+ }
+ },
+
+ create(context) {
+
+ const options = context.options[0] || {},
+ ignoreChainWithDepth = options.ignoreChainWithDepth || 2;
+
+ const sourceCode = context.getSourceCode();
+
+ /**
+ * Get the prefix of a given MemberExpression node.
+ * If the MemberExpression node is a computed value it returns a
+ * left bracket. If not it returns a period.
+ * @param {ASTNode} node A MemberExpression node to get
+ * @returns {string} The prefix of the node.
+ */
+ function getPrefix(node) {
+ if (node.computed) {
+ if (node.optional) {
+ return "?.[";
+ }
+ return "[";
+ }
+ if (node.optional) {
+ return "?.";
+ }
+ return ".";
+ }
+
+ /**
+ * Gets the property text of a given MemberExpression node.
+ * If the text is multiline, this returns only the first line.
+ * @param {ASTNode} node A MemberExpression node to get.
+ * @returns {string} The property text of the node.
+ */
+ function getPropertyText(node) {
+ const prefix = getPrefix(node);
+ const lines = sourceCode.getText(node.property).split(astUtils.LINEBREAK_MATCHER);
+ const suffix = node.computed && lines.length === 1 ? "]" : "";
+
+ return prefix + lines[0] + suffix;
+ }
+
+ return {
+ "CallExpression:exit"(node) {
+ const callee = astUtils.skipChainExpression(node.callee);
+
+ if (callee.type !== "MemberExpression") {
+ return;
+ }
+
+ let parent = astUtils.skipChainExpression(callee.object);
+ let depth = 1;
+
+ while (parent && parent.callee) {
+ depth += 1;
+ parent = astUtils.skipChainExpression(astUtils.skipChainExpression(parent.callee).object);
+ }
+
+ if (depth > ignoreChainWithDepth && astUtils.isTokenOnSameLine(callee.object, callee.property)) {
+ const firstTokenAfterObject = sourceCode.getTokenAfter(callee.object, astUtils.isNotClosingParenToken);
+
+ context.report({
+ node: callee.property,
+ loc: {
+ start: firstTokenAfterObject.loc.start,
+ end: callee.loc.end
+ },
+ messageId: "expected",
+ data: {
+ callee: getPropertyText(callee)
+ },
+ fix(fixer) {
+ return fixer.insertTextBefore(firstTokenAfterObject, "\n");
+ }
+ });
+ }
+ }
+ };
+ }
+};