jscodeshift experiment: Object.keys(thing).map(k => thing[k]) --> Object.values(thing)

object-keys-map.ts

import { FileInfo, API, MemberExpression, CallExpression, Identifier } from 'jscodeshift';

function isExpression<T>(object: any, type: string): object is T {
	return object.hasOwnProperty('type') && object.type === type;
}

function isMemberExpression(object: any): object is MemberExpression {
	return isExpression<MemberExpression>(object, 'MemberExpression');
}

function isIdentifier(object: any): object is Identifier {
	return isExpression<Identifier>(object, 'Identifier');
}

function objectKeysMapToValues(fileInfo: FileInfo, api: API) {
	const j = api.jscodeshift;

	const root = j(fileInfo.source);

	root.find(j.CallExpression, {
		callee: {
			type: 'MemberExpression',
			object: {
				type: 'CallExpression',
				callee: {
					type: 'MemberExpression',
					object: {
						type: 'Identifier',
						name: 'Object'
					},
					property: {
						type: 'Identifier',
						name: 'keys'
					},
				},
			},
			property: {
				type: 'Identifier',
				name: 'map',
			},
		},
	})
	.replaceWith(nodePath => {
		const { node } = nodePath;

		// Ignore all nodes that are not "trivial", i.e. where the map is not a simple arrow expression
		const mapArgument = node.arguments[0];
		if (mapArgument.type !== 'ArrowFunctionExpression') {
			return node;
		}
		if (!isMemberExpression(mapArgument.body)) {
			return node;
		}
		if (!isIdentifier(mapArgument.params[0])) {
			return node;
		}
		const keysArgument = ((node.callee as MemberExpression).object as CallExpression).arguments[0];
		if (!isIdentifier(keysArgument)) {
			return node;
		}
		if (!(isIdentifier(mapArgument.body.object) && mapArgument.body.object.name === keysArgument.name)) {
			return node;
		}
		if (!(isIdentifier(mapArgument.body.property) && mapArgument.body.property.name === mapArgument.params[0].name)) {
			return node;
		}

		// Do the replacing with a simple 'Object.values(thing)
		return j.callExpression(
				j.memberExpression(j.identifier('Object'), j.identifier('values')),
				[j.identifier(keysArgument.name)]);
				
	});


	return root.toSource();
}

// Export for jscodeshift
objectKeysMapToValues.parser = 'ts';
export = objectKeysMapToValues;