diff --git a/.gitignore b/.gitignore
index 3d1322c33e89..35888493fa95 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,14 +4,14 @@
 node_modules
 *.map
 /src/compile/internal-exports.ts
-/compiler.js
-/index.js
-/internal.*
-/store.*
-/easing.js
-/motion.*
-/transition.js
-/animate.js
+/compiler.*js
+/index.*js
+/internal.*js
+/store.*js
+/easing.*js
+/motion.*js
+/transition.*js
+/animate.*js
 /scratch/
 /coverage/
 /coverage.lcov/
@@ -21,6 +21,7 @@ node_modules
 /test/sourcemaps/samples/*/output.css.map
 /yarn-error.log
 _actual*.*
+/dist
 
 /site/cypress/screenshots/
 /site/__sapper__/
diff --git a/animate.d.ts b/animate.d.ts
new file mode 100644
index 000000000000..3284bfd8c09e
--- /dev/null
+++ b/animate.d.ts
@@ -0,0 +1 @@
+export * from './dist/animate';
diff --git a/compiler.d.ts b/compiler.d.ts
new file mode 100644
index 000000000000..977efefb6d7d
--- /dev/null
+++ b/compiler.d.ts
@@ -0,0 +1 @@
+export * from './dist/compiler';
diff --git a/easing.d.ts b/easing.d.ts
new file mode 100644
index 000000000000..c07764f4f04b
--- /dev/null
+++ b/easing.d.ts
@@ -0,0 +1 @@
+export * from './dist/easing';
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 000000000000..e4ddc9027ee3
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1 @@
+export * from './dist/index';
diff --git a/index.mjs b/index.mjs
deleted file mode 100644
index ee5b575171e3..000000000000
--- a/index.mjs
+++ /dev/null
@@ -1,10 +0,0 @@
-export {
-	onMount,
-	onDestroy,
-	beforeUpdate,
-	afterUpdate,
-	setContext,
-	getContext,
-	tick,
-	createEventDispatcher
-} from './internal';
diff --git a/internal.d.ts b/internal.d.ts
new file mode 100644
index 000000000000..be034cd88a81
--- /dev/null
+++ b/internal.d.ts
@@ -0,0 +1 @@
+export * from './dist/internal';
diff --git a/motion.d.ts b/motion.d.ts
new file mode 100644
index 000000000000..2fdaa86c4e7b
--- /dev/null
+++ b/motion.d.ts
@@ -0,0 +1 @@
+export * from './dist/motion';
diff --git a/package.json b/package.json
index b32e19786fd3..7963e2178dca 100644
--- a/package.json
+++ b/package.json
@@ -30,10 +30,10 @@
     "prepare": "npm run build && npm run tsd",
     "dev": "rollup -cw",
     "pretest": "npm run build",
-    "posttest": "agadoo src/internal/index.js",
+    "posttest": "agadoo internal.mjs",
     "prepublishOnly": "export PUBLISH=true && npm run lint && npm test",
-    "tsd": "tsc -d src/store.ts --outDir .",
-    "typecheck": "tsc --noEmit"
+    "tsd": "tsc -p . --emitDeclarationOnly",
+    "typecheck": "tsc -p . --noEmit"
   },
   "repository": {
     "type": "git",
diff --git a/rollup.config.js b/rollup.config.js
index 0d19e59d4ade..9fd49f3e8f97 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -9,10 +9,19 @@ import pkg from './package.json';
 
 const is_publish = !!process.env.PUBLISH;
 
+const tsPlugin = is_publish
+	? typescript({
+		include: 'src/**',
+		typescript: require('typescript')
+	})
+	: sucrase({
+		transforms: ['typescript']
+	});
+
 export default [
 	/* internal.[m]js */
 	{
-		input: `src/internal/index.js`,
+		input: `src/internal/index.ts`,
 		output: [
 			{
 				file: `internal.mjs`,
@@ -26,19 +35,22 @@ export default [
 			}
 		],
 		external: id => id.startsWith('svelte/'),
-		plugins: [{
-			generateBundle(options, bundle) {
-				const mod = bundle['internal.mjs'];
-				if (mod) {
-					fs.writeFileSync('src/compile/internal-exports.ts', `// This file is automatically generated\nexport default new Set(${JSON.stringify(mod.exports)});`);
+
+		plugins: [
+			tsPlugin,
+			{
+				generateBundle(options, bundle) {
+					const mod = bundle['internal.mjs'];
+					if (mod) {
+						fs.writeFileSync('src/compile/internal-exports.ts', `// This file is automatically generated\nexport default new Set(${JSON.stringify(mod.exports)});`);
+					}
 				}
-			}
-		}]
+			}]
 	},
 
 	/* compiler.js */
 	{
-		input: 'src/index.ts',
+		input: 'src/compiler.ts',
 		plugins: [
 			replace({
 				__VERSION__: pkg.version
@@ -48,15 +60,7 @@ export default [
 				include: ['node_modules/**']
 			}),
 			json(),
-			is_publish
-				? typescript({
-					include: 'src/**',
-					exclude: 'src/internal/**',
-					typescript: require('typescript')
-				})
-				: sucrase({
-					transforms: ['typescript']
-				})
+			tsPlugin
 		],
 		output: {
 			file: 'compiler.js',
@@ -71,7 +75,7 @@ export default [
 
 	/* motion.mjs */
 	{
-		input: `src/motion/index.js`,
+		input: `src/motion/index.ts`,
 		output: [
 			{
 				file: `motion.mjs`,
@@ -84,46 +88,30 @@ export default [
 				paths: id => id.startsWith('svelte/') && id.replace('svelte', '.')
 			}
 		],
+		plugins: [
+			tsPlugin
+		],
 		external: id => id.startsWith('svelte/')
 	},
 
-	/* store.mjs */
-	{
-		input: `src/store.ts`,
+	// everything else
+	...['index', 'easing', 'transition', 'animate', 'store'].map(name => ({
+		input: `src/${name}.ts`,
 		output: [
 			{
-				file: `store.mjs`,
+				file: `${name}.mjs`,
 				format: 'esm',
 				paths: id => id.startsWith('svelte/') && id.replace('svelte', '.')
 			},
 			{
-				file: `store.js`,
+				file: `${name}.js`,
 				format: 'cjs',
 				paths: id => id.startsWith('svelte/') && id.replace('svelte', '.')
 			}
 		],
 		plugins: [
-			is_publish
-				? typescript({
-					include: 'src/**',
-					exclude: 'src/internal/**',
-					typescript: require('typescript')
-				})
-				: sucrase({
-					transforms: ['typescript']
-				})
+			tsPlugin
 		],
 		external: id => id.startsWith('svelte/')
-	},
-
-	// everything else
-	...['index', 'easing', 'transition', 'animate'].map(name => ({
-		input: `${name}.mjs`,
-		output: {
-			file: `${name}.js`,
-			format: 'cjs',
-			paths: id => id.startsWith('svelte/') && id.replace('svelte', '.')
-		},
-		external: id => id !== `${name}.mjs`
 	}))
 ];
diff --git a/animate.mjs b/src/animate.ts
similarity index 86%
rename from animate.mjs
rename to src/animate.ts
index f22fabe401c9..cf64cd060a13 100644
--- a/animate.mjs
+++ b/src/animate.ts
@@ -1,5 +1,5 @@
-import { cubicOut } from './easing';
-import { is_function } from './internal';
+import { cubicOut } from 'svelte/easing';
+import { is_function } from 'svelte/internal';
 
 export function flip(node, animation, params) {
 	const style = getComputedStyle(node);
@@ -22,4 +22,4 @@ export function flip(node, animation, params) {
 		easing,
 		css: (t, u) => `transform: ${transform} translate(${u * dx}px, ${u * dy}px);`
 	};
-}
\ No newline at end of file
+}
diff --git a/src/compile/index.ts b/src/compile/index.ts
index 526d8abaeb2a..dac75f23e0e5 100644
--- a/src/compile/index.ts
+++ b/src/compile/index.ts
@@ -1,4 +1,4 @@
-import { assign } from '../internal';
+import { assign } from '../internal/index';
 import Stats from '../Stats';
 import parse from '../parse/index';
 import render_dom from './render-dom/index';
diff --git a/src/compile/render-dom/wrappers/RawMustacheTag.ts b/src/compile/render-dom/wrappers/RawMustacheTag.ts
index d8f863c67433..326852bb1865 100644
--- a/src/compile/render-dom/wrappers/RawMustacheTag.ts
+++ b/src/compile/render-dom/wrappers/RawMustacheTag.ts
@@ -1,7 +1,7 @@
 import Renderer from '../Renderer';
 import Block from '../Block';
 import Tag from './shared/Tag';
-import Wrapper from './shared/wrapper';
+import Wrapper from './shared/Wrapper';
 import deindent from '../../utils/deindent';
 import MustacheTag from '../../nodes/MustacheTag';
 import RawMustacheTag from '../../nodes/RawMustacheTag';
diff --git a/src/compiler.ts b/src/compiler.ts
new file mode 100644
index 000000000000..4987c18a15be
--- /dev/null
+++ b/src/compiler.ts
@@ -0,0 +1,6 @@
+export { default as compile } from './compile/index';
+export { default as parse } from './parse/index';
+export { default as preprocess } from './preprocess/index';
+export { walk } from 'estree-walker';
+
+export const VERSION = '__VERSION__';
\ No newline at end of file
diff --git a/easing.mjs b/src/easing.ts
similarity index 98%
rename from easing.mjs
rename to src/easing.ts
index 4fc625c24f97..7a762394c2ad 100644
--- a/easing.mjs
+++ b/src/easing.ts
@@ -3,7 +3,7 @@ Adapted from https://github.com/mattdesl
 Distributed under MIT License https://github.com/mattdesl/eases/blob/master/LICENSE.md
 */
 
-export { identity as linear } from './internal';
+export { identity as linear } from 'svelte/internal';
 
 export function backInOut(t) {
 	const s = 1.70158 * 1.525;
diff --git a/src/index.ts b/src/index.ts
index 4987c18a15be..40928da8a0eb 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,6 +1,10 @@
-export { default as compile } from './compile/index';
-export { default as parse } from './parse/index';
-export { default as preprocess } from './preprocess/index';
-export { walk } from 'estree-walker';
-
-export const VERSION = '__VERSION__';
\ No newline at end of file
+export {
+	onMount,
+	onDestroy,
+	beforeUpdate,
+	afterUpdate,
+	setContext,
+	getContext,
+	tick,
+	createEventDispatcher
+} from 'svelte/internal';
diff --git a/src/internal/Component.js b/src/internal/Component.ts
similarity index 89%
rename from src/internal/Component.js
rename to src/internal/Component.ts
index 871dbd6054de..714d15df343e 100644
--- a/src/internal/Component.js
+++ b/src/internal/Component.ts
@@ -1,7 +1,23 @@
-import { add_render_callback, flush, schedule_update, dirty_components } from './scheduler.js';
-import { current_component, set_current_component } from './lifecycle.js';
-import { blank_object, is_function, run, run_all, noop } from './utils.js';
-import { children } from './dom.js';
+import { add_render_callback, flush, schedule_update, dirty_components } from './scheduler';
+import { current_component, set_current_component } from './lifecycle';
+import { blank_object, is_function, run, run_all, noop } from './utils';
+import { children } from './dom';
+
+interface T$$ {
+	dirty: null;
+	ctx: null|any;
+	bound: any;
+	update: () => void;
+	callbacks: any;
+	after_render: any[];
+	props: any;
+	fragment: null|any;
+	not_equal: any;
+	before_render: any[];
+	context: Map<any, any>;
+	on_mount: any[];
+	on_destroy: any[]
+}
 
 export function bind(component, name, callback) {
 	if (component.$$.props.indexOf(name) === -1) return;
@@ -59,7 +75,7 @@ export function init(component, options, instance, create_fragment, not_equal, p
 
 	const props = options.props || {};
 
-	const $$ = component.$$ = {
+	const $$: T$$ = component.$$ = {
 		fragment: null,
 		ctx: null,
 
@@ -99,9 +115,9 @@ export function init(component, options, instance, create_fragment, not_equal, p
 
 	if (options.target) {
 		if (options.hydrate) {
-			$$.fragment.l(children(options.target));
+			$$.fragment!.l(children(options.target));
 		} else {
-			$$.fragment.c();
+			$$.fragment!.c();
 		}
 
 		if (options.intro && component.$$.fragment.i) component.$$.fragment.i();
@@ -115,13 +131,16 @@ export function init(component, options, instance, create_fragment, not_equal, p
 export let SvelteElement;
 if (typeof HTMLElement !== 'undefined') {
 	SvelteElement = class extends HTMLElement {
+		$$: T$$;
 		constructor() {
 			super();
 			this.attachShadow({ mode: 'open' });
 		}
 
 		connectedCallback() {
+			// @ts-ignore todo: improve typings
 			for (const key in this.$$.slotted) {
+				// @ts-ignore todo: improve typings
 				this.appendChild(this.$$.slotted[key]);
 			}
 		}
@@ -153,6 +172,8 @@ if (typeof HTMLElement !== 'undefined') {
 }
 
 export class SvelteComponent {
+	$$: T$$;
+
 	$destroy() {
 		destroy(this, true);
 		this.$destroy = noop;
diff --git a/src/internal/animations.js b/src/internal/animations.ts
similarity index 92%
rename from src/internal/animations.js
rename to src/internal/animations.ts
index 8d55c196eed3..b6c7ae2df21a 100644
--- a/src/internal/animations.js
+++ b/src/internal/animations.ts
@@ -1,6 +1,6 @@
-import { identity as linear, noop, now } from './utils.js';
-import { loop } from './loop.js';
-import { create_rule, delete_rule } from './style_manager.js';
+import { identity as linear, noop, now } from './utils';
+import { loop } from './loop';
+import { create_rule, delete_rule } from './style_manager';
 
 export function create_animation(node, from, fn, params) {
 	if (!from) return noop;
@@ -90,4 +90,4 @@ export function fix_position(node) {
 			node.style.transform = `${transform} translate(${a.left - b.left}px, ${a.top - b.top}px)`;
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/src/internal/await-block.js b/src/internal/await-block.ts
similarity index 89%
rename from src/internal/await-block.js
rename to src/internal/await-block.ts
index 9e14c50342d2..9527b000ca44 100644
--- a/src/internal/await-block.js
+++ b/src/internal/await-block.ts
@@ -1,11 +1,11 @@
-import { assign, is_promise } from './utils.js';
-import { check_outros, group_outros, on_outro } from './transitions.js';
-import { flush } from '../internal/scheduler.js';
+import { assign, is_promise } from './utils';
+import { check_outros, group_outros, on_outro } from './transitions';
+import { flush } from '../internal/scheduler';
 
 export function handle_promise(promise, info) {
 	const token = info.token = {};
 
-	function update(type, index, key, value) {
+	function update(type, index, key?, value?) {
 		if (info.token !== token) return;
 
 		info.resolved = key && { [key]: value };
@@ -61,4 +61,4 @@ export function handle_promise(promise, info) {
 
 		info.resolved = { [info.value]: promise };
 	}
-}
\ No newline at end of file
+}
diff --git a/src/internal/dom.js b/src/internal/dom.ts
similarity index 80%
rename from src/internal/dom.js
rename to src/internal/dom.ts
index 46ffaa84727c..293040ce202e 100644
--- a/src/internal/dom.js
+++ b/src/internal/dom.ts
@@ -1,28 +1,28 @@
-export function append(target, node) {
+export function append(target:Node, node:Node) {
 	target.appendChild(node);
 }
 
-export function insert(target, node, anchor) {
+export function insert(target: Node, node: Node, anchor?:Node) {
 	target.insertBefore(node, anchor || null);
 }
 
-export function detach(node) {
+export function detach(node: Node) {
 	node.parentNode.removeChild(node);
 }
 
-export function detach_between(before, after) {
+export function detach_between(before: Node, after: Node) {
 	while (before.nextSibling && before.nextSibling !== after) {
 		before.parentNode.removeChild(before.nextSibling);
 	}
 }
 
-export function detach_before(after) {
+export function detach_before(after:Node) {
 	while (after.previousSibling) {
 		after.parentNode.removeChild(after.previousSibling);
 	}
 }
 
-export function detach_after(before) {
+export function detach_after(before:Node) {
 	while (before.nextSibling) {
 		before.parentNode.removeChild(before.nextSibling);
 	}
@@ -34,25 +34,30 @@ export function destroy_each(iterations, detaching) {
 	}
 }
 
-export function element(name) {
-	return document.createElement(name);
+export function element<K extends keyof HTMLElementTagNameMap>(name: K) {
+	return document.createElement<K>(name);
 }
 
-export function object_without_properties(obj, exclude) {
-	const target = {};
+export function object_without_properties<T,K extends keyof T>(obj:T, exclude: K[]) {
+	const target = {} as Pick<T, Exclude<keyof T, K>>;
 	for (const k in obj) {
-		if (Object.prototype.hasOwnProperty.call(obj, k) && exclude.indexOf(k) === -1) {
+		if (
+			Object.prototype.hasOwnProperty.call(obj, k)
+			// @ts-ignore
+			&& exclude.indexOf(k) === -1
+		) {
+			// @ts-ignore
 			target[k] = obj[k];
 		}
 	}
 	return target;
 }
 
-export function svg_element(name) {
+export function svg_element(name:string):SVGElement {
 	return document.createElementNS('http://www.w3.org/2000/svg', name);
 }
 
-export function text(data) {
+export function text(data:string) {
 	return document.createTextNode(data);
 }
 
@@ -64,7 +69,7 @@ export function empty() {
 	return text('');
 }
 
-export function listen(node, event, handler, options) {
+export function listen(node: Node, event: string, handler: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | EventListenerOptions) {
 	node.addEventListener(event, handler, options);
 	return () => node.removeEventListener(event, handler, options);
 }
@@ -72,6 +77,7 @@ export function listen(node, event, handler, options) {
 export function prevent_default(fn) {
 	return function(event) {
 		event.preventDefault();
+		// @ts-ignore
 		return fn.call(this, event);
 	};
 }
@@ -79,16 +85,17 @@ export function prevent_default(fn) {
 export function stop_propagation(fn) {
 	return function(event) {
 		event.stopPropagation();
+		// @ts-ignore
 		return fn.call(this, event);
 	};
 }
 
-export function attr(node, attribute, value) {
+export function attr(node: Element, attribute: string, value?: string) {
 	if (value == null) node.removeAttribute(attribute);
 	else node.setAttribute(attribute, value);
 }
 
-export function set_attributes(node, attributes) {
+export function set_attributes(node: HTMLElement, attributes: { [x: string]: string; }) {
 	for (const key in attributes) {
 		if (key === 'style') {
 			node.style.cssText = attributes[key];
@@ -243,8 +250,8 @@ export function toggle_class(element, name, toggle) {
 	element.classList[toggle ? 'add' : 'remove'](name);
 }
 
-export function custom_event(type, detail) {
-	const e = document.createEvent('CustomEvent');
+export function custom_event<T=any>(type: string, detail?: T) {
+	const e: CustomEvent<T> = document.createEvent('CustomEvent');
 	e.initCustomEvent(type, false, false, detail);
 	return e;
 }
diff --git a/src/internal/index.js b/src/internal/index.js
deleted file mode 100644
index f3654f6b7791..000000000000
--- a/src/internal/index.js
+++ /dev/null
@@ -1,12 +0,0 @@
-export * from './animations.js';
-export * from './await-block.js';
-export * from './dom.js';
-export * from './keyed-each.js';
-export * from './lifecycle.js';
-export * from './loop.js';
-export * from './scheduler.js';
-export * from './spread.js';
-export * from './ssr.js';
-export * from './transitions.js';
-export * from './utils.js';
-export * from './Component.js';
\ No newline at end of file
diff --git a/src/internal/index.ts b/src/internal/index.ts
new file mode 100644
index 000000000000..6487f04525f3
--- /dev/null
+++ b/src/internal/index.ts
@@ -0,0 +1,12 @@
+export * from './animations';
+export * from './await-block';
+export * from './dom';
+export * from './keyed-each';
+export * from './lifecycle';
+export * from './loop';
+export * from './scheduler';
+export * from './spread';
+export * from './ssr';
+export * from './transitions';
+export * from './utils';
+export * from './Component';
diff --git a/src/internal/keyed-each.js b/src/internal/keyed-each.ts
similarity index 98%
rename from src/internal/keyed-each.js
rename to src/internal/keyed-each.ts
index c40a1cc00bbd..0ec8b0940051 100644
--- a/src/internal/keyed-each.js
+++ b/src/internal/keyed-each.ts
@@ -1,4 +1,4 @@
-import { on_outro } from './transitions.js';
+import { on_outro } from './transitions';
 
 export function destroy_block(block, lookup) {
 	block.d(1);
@@ -110,4 +110,4 @@ export function measure(blocks) {
 	let i = blocks.length;
 	while (i--) rects[blocks[i].key] = blocks[i].node.getBoundingClientRect();
 	return rects;
-}
\ No newline at end of file
+}
diff --git a/src/internal/lifecycle.js b/src/internal/lifecycle.ts
similarity index 100%
rename from src/internal/lifecycle.js
rename to src/internal/lifecycle.ts
diff --git a/src/internal/loop.js b/src/internal/loop.ts
similarity index 71%
rename from src/internal/loop.js
rename to src/internal/loop.ts
index 60c7df4d7096..73f118c234a3 100644
--- a/src/internal/loop.js
+++ b/src/internal/loop.ts
@@ -1,4 +1,6 @@
-import { now, raf } from './utils.js';
+import { now, raf } from './utils';
+
+export interface Task { abort(): void; promise: Promise<undefined> }
 
 const tasks = new Set();
 let running = false;
@@ -21,7 +23,7 @@ export function clear_loops() {
 	running = false;
 }
 
-export function loop(fn) {
+export function loop(fn: (number)=>void): Task {
 	let task;
 
 	if (!running) {
@@ -30,11 +32,11 @@ export function loop(fn) {
 	}
 
 	return {
-		promise: new Promise(fulfil => {
+		promise: new Promise<undefined>(fulfil => {
 			tasks.add(task = [fn, fulfil]);
 		}),
 		abort() {
 			tasks.delete(task);
 		}
 	};
-}
\ No newline at end of file
+}
diff --git a/src/internal/scheduler.js b/src/internal/scheduler.ts
similarity index 94%
rename from src/internal/scheduler.js
rename to src/internal/scheduler.ts
index 749c3971dcb2..a26a4f8c337c 100644
--- a/src/internal/scheduler.js
+++ b/src/internal/scheduler.ts
@@ -1,5 +1,5 @@
-import { run_all } from './utils.js';
-import { set_current_component } from './lifecycle.js';
+import { run_all } from './utils';
+import { set_current_component } from './lifecycle';
 
 export const dirty_components = [];
 export const intros = { enabled: false };
diff --git a/src/internal/spread.js b/src/internal/spread.ts
similarity index 100%
rename from src/internal/spread.js
rename to src/internal/spread.ts
diff --git a/src/internal/ssr.js b/src/internal/ssr.ts
similarity index 97%
rename from src/internal/ssr.js
rename to src/internal/ssr.ts
index e8d96c609c88..aaa391b4dcf5 100644
--- a/src/internal/ssr.js
+++ b/src/internal/ssr.ts
@@ -1,5 +1,5 @@
-import { set_current_component, current_component } from './lifecycle.js';
-import { run_all, blank_object } from './utils.js';
+import { set_current_component, current_component } from './lifecycle';
+import { run_all, blank_object } from './utils';
 
 export const invalid_attribute_name_character = /[\s'">/=\u{FDD0}-\u{FDEF}\u{FFFE}\u{FFFF}\u{1FFFE}\u{1FFFF}\u{2FFFE}\u{2FFFF}\u{3FFFE}\u{3FFFF}\u{4FFFE}\u{4FFFF}\u{5FFFE}\u{5FFFF}\u{6FFFE}\u{6FFFF}\u{7FFFE}\u{7FFFF}\u{8FFFE}\u{8FFFF}\u{9FFFE}\u{9FFFF}\u{AFFFE}\u{AFFFF}\u{BFFFE}\u{BFFFF}\u{CFFFE}\u{CFFFF}\u{DFFFE}\u{DFFFF}\u{EFFFE}\u{EFFFF}\u{FFFFE}\u{FFFFF}\u{10FFFE}\u{10FFFF}]/u;
 // https://html.spec.whatwg.org/multipage/syntax.html#attributes-2
@@ -117,4 +117,4 @@ export function get_store_value(store) {
 	let value;
 	store.subscribe(_ => value = _)();
 	return value;
-}
\ No newline at end of file
+}
diff --git a/src/internal/style_manager.js b/src/internal/style_manager.ts
similarity index 93%
rename from src/internal/style_manager.js
rename to src/internal/style_manager.ts
index 367947039997..9ef1b12d1cba 100644
--- a/src/internal/style_manager.js
+++ b/src/internal/style_manager.ts
@@ -1,5 +1,5 @@
-import { element } from './dom.js';
-import { raf } from './utils.js';
+import { element } from './dom';
+import { raf } from './utils';
 
 let stylesheet;
 let active = 0;
@@ -44,7 +44,7 @@ export function create_rule(node, a, b, duration, delay, ease, fn, uid = 0) {
 	return name;
 }
 
-export function delete_rule(node, name) {
+export function delete_rule(node, name?) {
 	node.style.animation = (node.style.animation || '')
 		.split(', ')
 		.filter(name
@@ -63,4 +63,4 @@ export function clear_rules() {
 		while (i--) stylesheet.deleteRule(i);
 		current_rules = {};
 	});
-}
\ No newline at end of file
+}
diff --git a/src/internal/transitions.js b/src/internal/transitions.ts
similarity index 95%
rename from src/internal/transitions.js
rename to src/internal/transitions.ts
index af15e8969eb8..04942e3d16ea 100644
--- a/src/internal/transitions.js
+++ b/src/internal/transitions.ts
@@ -1,8 +1,8 @@
-import { identity as linear, noop, now, run_all } from './utils.js';
-import { loop } from './loop.js';
-import { create_rule, delete_rule } from './style_manager.js';
-import { custom_event } from './dom.js';
-import { add_render_callback } from './scheduler.js';
+import { identity as linear, noop, now, run_all } from './utils';
+import { loop } from './loop';
+import { create_rule, delete_rule } from './style_manager';
+import { custom_event } from './dom';
+import { add_render_callback } from './scheduler';
 
 let promise;
 
@@ -229,6 +229,7 @@ export function create_bidirectional_transition(node, fn, params, intro) {
 		};
 
 		if (!b) {
+			// @ts-ignore todo: improve typings
 			program.group = outros;
 			outros.remaining += 1;
 		}
@@ -309,4 +310,4 @@ export function create_bidirectional_transition(node, fn, params, intro) {
 			running_program = pending_program = null;
 		}
 	};
-}
\ No newline at end of file
+}
diff --git a/src/internal/utils.js b/src/internal/utils.ts
similarity index 98%
rename from src/internal/utils.js
rename to src/internal/utils.ts
index 7823a5b920a1..c562cd02b6bc 100644
--- a/src/internal/utils.js
+++ b/src/internal/utils.ts
@@ -82,7 +82,7 @@ export function exclude_internal_props(props) {
 
 const is_client = typeof window !== 'undefined';
 
-export let now = is_client
+export let now: () => number = is_client
 	? () => window.performance.now()
 	: () => Date.now();
 
@@ -95,4 +95,4 @@ export function set_now(fn) {
 
 export function set_raf(fn) {
 	raf = fn;
-}
\ No newline at end of file
+}
diff --git a/src/motion/index.js b/src/motion/index.js
deleted file mode 100644
index e0e9bcf1aee5..000000000000
--- a/src/motion/index.js
+++ /dev/null
@@ -1,2 +0,0 @@
-export * from './spring.js';
-export * from './tweened.js';
\ No newline at end of file
diff --git a/src/motion/index.ts b/src/motion/index.ts
new file mode 100644
index 000000000000..ea6c646dd94b
--- /dev/null
+++ b/src/motion/index.ts
@@ -0,0 +1,2 @@
+export * from './spring';
+export * from './tweened';
diff --git a/src/motion/spring.js b/src/motion/spring.ts
similarity index 73%
rename from src/motion/spring.js
rename to src/motion/spring.ts
index 8b280366b2eb..3977c08f79be 100644
--- a/src/motion/spring.js
+++ b/src/motion/spring.ts
@@ -1,6 +1,6 @@
-import { writable } from 'svelte/store'; // eslint-disable-line import/no-unresolved
-import { loop, now } from 'svelte/internal'; // eslint-disable-line import/no-unresolved
-import { is_date } from './utils.js';
+import { Readable, writable } from 'svelte/store';
+import { loop, now, Task } from 'svelte/internal';
+import { is_date } from './utils';
 
 function tick_spring(ctx, last_value, current_value, target_value) {
 	if (typeof current_value === 'number' || is_date(current_value)) {
@@ -27,25 +27,41 @@ function tick_spring(ctx, last_value, current_value, target_value) {
 			next_value[k] = tick_spring(ctx, last_value[k], current_value[k], target_value[k]);
 		return next_value;
 	} else {
-		throw new Error(`Cannot spring ${typeof value} values`);
+		throw new Error(`Cannot spring ${typeof current_value} values`);
 	}
 }
 
-export function spring(value, opts = {}) {
+interface SpringOpts {
+	stiffness?: number,
+	damping?: number,
+	precision?: number,
+}
+
+type SpringUpdateOpts = { hard?: any; soft?: string | number | boolean; };
+
+interface Spring<T=any> extends Readable<T>{
+	set: (new_value: T, opts?: SpringUpdateOpts) => (Promise<T> | Promise<T>);
+	precision: number;
+	update: (fn, opts: SpringUpdateOpts) => Promise<T>;
+	damping: number;
+	stiffness: number
+}
+
+export function spring<T=any>(value: T, opts: SpringOpts = {}) {
 	const store = writable(value);
 	const { stiffness = 0.15, damping = 0.8, precision = 0.01 } = opts;
 
-	let last_time;
-	let task;
-	let current_token;
-	let last_value = value;
-	let target_value = value;
+	let last_time: number;
+	let task: Task;
+	let current_token: object;
+	let last_value:T = value;
+	let target_value:T = value;
 
 	let inv_mass = 1;
 	let inv_mass_recovery_rate = 0;
 	let cancel_task = false;
 
-	function set(new_value, opts = {}) {
+	function set(new_value: any, opts: SpringUpdateOpts={}) {
 		target_value = new_value;
 		const token = current_token = {};
 
@@ -100,9 +116,9 @@ export function spring(value, opts = {}) {
 		});
 	}
 
-	const spring = {
+	const spring: Spring = {
 		set,
-		update: (fn, opts) => set(fn(target_value, value), opts),
+		update: (fn, opts:SpringUpdateOpts) => set(fn(target_value, value), opts),
 		subscribe: store.subscribe,
 		stiffness,
 		damping,
diff --git a/src/motion/tweened.js b/src/motion/tweened.ts
similarity index 98%
rename from src/motion/tweened.js
rename to src/motion/tweened.ts
index 45520832b79b..3b2d0ef5a2cd 100644
--- a/src/motion/tweened.js
+++ b/src/motion/tweened.ts
@@ -1,7 +1,7 @@
 import { writable } from 'svelte/store'; // eslint-disable-line import/no-unresolved
 import { assign, loop, now } from 'svelte/internal'; // eslint-disable-line import/no-unresolved
 import { linear } from 'svelte/easing'; // eslint-disable-line import/no-unresolved
-import { is_date } from './utils.js';
+import { is_date } from './utils';
 
 function get_interpolator(a, b) {
 	if (a === b || a !== a) return () => a;
@@ -109,4 +109,4 @@ export function tweened(value, defaults = {}) {
 		update: (fn, opts) => set(fn(target_value, value), opts),
 		subscribe: store.subscribe
 	};
-}
\ No newline at end of file
+}
diff --git a/src/motion/utils.js b/src/motion/utils.ts
similarity index 63%
rename from src/motion/utils.js
rename to src/motion/utils.ts
index 97a764bf4648..f8bfcce14c9f 100644
--- a/src/motion/utils.js
+++ b/src/motion/utils.ts
@@ -1,3 +1,3 @@
-export function is_date(obj) {
+export function is_date(obj: any) {
 	return Object.prototype.toString.call(obj) === '[object Date]';
-}
\ No newline at end of file
+}
diff --git a/src/store.ts b/src/store.ts
index b0ee41fc8d02..361632b61d03 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -1,4 +1,4 @@
-import { run_all, noop, safe_not_equal, is_function } from './internal/utils';
+import { run_all, noop, safe_not_equal, is_function } from 'svelte/internal';
 
 /** Callback to inform of a value updates. */
 type Subscriber<T> = (value: T) => void;
diff --git a/transition.mjs b/src/transition.ts
similarity index 97%
rename from transition.mjs
rename to src/transition.ts
index 857fd03165d6..20619ee13178 100644
--- a/transition.mjs
+++ b/src/transition.ts
@@ -1,5 +1,5 @@
-import { cubicOut, cubicInOut } from './easing';
-import { assign, is_function } from './internal';
+import { cubicOut, cubicInOut } from 'svelte/easing';
+import { assign, is_function } from 'svelte/internal';
 
 export function fade(node, {
 	delay = 0,
@@ -179,4 +179,4 @@ export function crossfade({ fallback, ...defaults }) {
 		transition(to_send, to_receive, false),
 		transition(to_receive, to_send, true)
 	];
-}
\ No newline at end of file
+}
diff --git a/src/utils/indentation.ts b/src/utils/indentation.ts
index 765a62bfbf8a..54ededc37d99 100644
--- a/src/utils/indentation.ts
+++ b/src/utils/indentation.ts
@@ -54,4 +54,4 @@ export function add_indentation(code: MagicString, node: Node, levels = 1) {
 
 		code.appendLeft(index + 1, indent);
 	}
-}
\ No newline at end of file
+}
diff --git a/store.d.ts b/store.d.ts
new file mode 100644
index 000000000000..2c1307011b74
--- /dev/null
+++ b/store.d.ts
@@ -0,0 +1 @@
+export * from './dist/store';
diff --git a/transition.d.ts b/transition.d.ts
new file mode 100644
index 000000000000..54d5f036da38
--- /dev/null
+++ b/transition.d.ts
@@ -0,0 +1 @@
+export * from './dist/transition';
diff --git a/tsconfig.json b/tsconfig.json
index fdb7367e054d..994bc61b8534 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,18 +1,35 @@
 {
-    "compilerOptions": {
-        "target": "ES6",
-        "diagnostics": true,
-        "noImplicitThis": true,
-        "noEmitOnError": true,
-        "allowJs": true,
-        "lib": ["es5", "es6", "dom"],
-        "importHelpers": true,
-        "moduleResolution": "node"
-    },
-    "include": [
-        "src"
-    ],
-    "exclude": [
-        "node_modules"
-    ]
+	"compilerOptions": {
+		"target": "es2015",
+		"module": "es6",
+		"declarationDir": "./dist",
+		"outDir": "./dist",
+		"declaration": true,
+		"noImplicitThis": true,
+		"noEmitOnError": true,
+		"lib": [
+			"es5",
+			"es6",
+			"dom",
+			"es2015"
+		],
+		"importHelpers": true,
+		"moduleResolution": "node",
+		"baseUrl": ".",
+		"paths": {
+			"svelte/internal": ["./src/internal"],
+			"svelte/easing": ["./src/easing"],
+			"svelte/motion": ["./src/motion"],
+			"svelte/store": ["./src/store"]
+		},
+		"typeRoots": [
+			"node_modules/@types"
+		]
+	},
+	"include": [
+		"src/**/*"
+	],
+	"exclude": [
+		"dist"
+	]
 }