feat: add concat-map

codemods/concat-map/index.js

@@ -0,0 +1,25 @@
+import jscodeshift from 'jscodeshift';
+import { transformArrayMethod } from '../shared.js';
+
+/**
+ * @typedef {import('../../types.js').Codemod} Codemod
+ * @typedef {import('../../types.js').CodemodOptions} CodemodOptions
+ */
+
+/**
+ * @param {CodemodOptions} [options]
+ * @returns {Codemod}
+ */
+export default function (options) {
+	return {
+		name: 'concat-map',
+		transform: ({ file }) => {
+			const j = jscodeshift;
+			const root = j(file.source);
+
+			const dirty = transformArrayMethod('concat-map', 'flatMap', root, j);
+
+			return dirty ? root.toSource(options) : file.source;
+		},
+	};
+}

test/fixtures/concat-map/case-1/after.js

@@ -0,0 +1,8 @@
+var assert = require("assert");
+
+var xs = [1, 2, 3, 4, 5, 6];
+var ys = xs.flatMap(function (x) {
+  return x % 2 ? [x - 0.1, x, x + 0.1] : [];
+});
+
+assert.deepEqual(ys, [0.9, 1, 1.1, 2.9, 3, 3.1, 4.9, 5, 5.1]);

test/fixtures/concat-map/case-1/before.js

@@ -0,0 +1,9 @@
+var concatMap = require("concat-map");
+var assert = require("assert");
+
+var xs = [1, 2, 3, 4, 5, 6];
+var ys = concatMap(xs, function (x) {
+  return x % 2 ? [x - 0.1, x, x + 0.1] : [];
+});
+
+assert.deepEqual(ys, [0.9, 1, 1.1, 2.9, 3, 3.1, 4.9, 5, 5.1]);

test/fixtures/concat-map/case-1/result.js

@@ -0,0 +1,8 @@
+var assert = require("assert");
+
+var xs = [1, 2, 3, 4, 5, 6];
+var ys = xs.flatMap(function (x) {
+  return x % 2 ? [x - 0.1, x, x + 0.1] : [];
+});
+
+assert.deepEqual(ys, [0.9, 1, 1.1, 2.9, 3, 3.1, 4.9, 5, 5.1]);