diff --git a/ix.js/ix.d.ts b/ix.js/ix.d.ts
new file mode 100644
index 000000000..5de2361dd
--- /dev/null
+++ b/ix.js/ix.d.ts
@@ -0,0 +1,114 @@
+///<reference path="l2o.d.ts"/>
+
+declare module Ix {
+
+	export interface Comparer<T1, T2> {
+		(item1: T1, item2: T2): number;
+	}
+
+	export interface Observer<T> {
+		onNext? (value: T): void;
+		onError? (error: Error): void;
+		onCompleted? (): void;
+	}
+
+	export interface Enumerable<T> {
+		isEmpty(): boolean;
+
+		minBy<TKey>(keySelector: (item: T) => TKey, comparer: Comparer<TKey, TKey>): Enumerable<T>;
+		minBy(keySelector: (item: T) => number): Enumerable<T>;
+		maxBy<TKey>(keySelector: (item: T) => TKey, comparer: Comparer<TKey, TKey>): Enumerable<T>;
+		maxBy(keySelector: (item: T) => number): Enumerable<T>;
+
+		share<TResult>(selector: (source: Enumerable<T>) => Enumerable<TResult>): Enumerable<TResult>;
+		share(): Enumerable<T>;
+
+		publish<TResult>(selector: (source: Enumerable<T>) => Enumerable<TResult>): Enumerable<TResult>;
+		publish(): Enumerable<T>;
+
+		memoize(): Enumerable<T>;
+
+		do(onNext: (value: T) => void, onError?: (error: Error) => void, onCompleted?: () => void): Enumerable<T>;
+		doAction(onNext: (value: T) => void, onError?: (error: Error) => void, onCompleted?: () => void): Enumerable<T>;
+		do(onbserver: Observer<T>): Enumerable<T>;
+		doAction(onbserver: Observer<T>): Enumerable<T>;
+
+		bufferWithCount(count: number, skip?: number): Enumerable<T>;
+
+		ignoreElements(): Enumerable<T>;
+
+		distinctBy<TKey>(keySelector: (item: T) => TKey, comparer?: EqualityComparer<TKey, TKey>): Enumerable<T>;
+
+		distinctUntilChanged<TKey>(keySelector: (item: T) => TKey, comparer?: EqualityComparer<TKey, TKey>): Enumerable<T>;
+		distinctUntilChanged(): Enumerable<T>;
+		// if need to set comparer without keySelector
+		distinctUntilChanged(_: boolean, comparer: EqualityComparer<T, T>): Enumerable<T>;
+
+		expand(selector: (item: T) => Enumerable<T>): Enumerable<T>;
+
+		startWith(...values: T[]): Enumerable<T>;
+
+		scan<TSeed, TAccumulator>(seed: TSeed, accumulate: (acc: TAccumulator, item: T) => TAccumulator): Enumerable<TAccumulator>;
+		scan(accumulate: (acc: T, item: T) => T): Enumerable<T>;
+
+		takeLast(count: number): Enumerable<T>;
+		skipLast(count: number): Enumerable<T>;
+
+		repeat(count?: number): Enumerable<T>;
+
+		catch(handler: (error: Error) => Enumerable<T>): Enumerable<T>;
+		catchException(handler: (error: Error) => Enumerable<T>): Enumerable<T>;
+		catch(second: Enumerable<T>, ...other: Enumerable<T>[]): Enumerable<T>;
+		catchException(second: Enumerable<T>, ...other: Enumerable<T>[]): Enumerable<T>;
+
+		// todo: Enumerable<Enumerable<T>>.catch(): Enumerable<T>
+		//catch<TInner, T extends Enumerable<TInner>>(): Enumerable<TInner>;
+
+		finally(finallyAction: () => void): Enumerable<T>;
+		finallyDo(finallyAction: () => void): Enumerable<T>;
+
+		onErrorResumeNext<T>(second: Enumerable<T>): Enumerable<T>;
+
+		retry(retryCount?: number): Enumerable<T>;
+
+		
+	}
+
+	export interface EnumerableStatic {
+		throw<T>(error: Error): Enumerable<T>;
+		throwException<T>(error: Error): Enumerable<T>;
+
+		defer<T>(enumerableFactory: () => Enumerable<T>): Enumerable<T>;
+
+		generate<TState, TResult>(
+			initialState: TState,
+			condition: Predicate<TState>,
+			iterate: (state: TState) => TState,
+			resultSelector: (state: TState) => TResult): Enumerable<TResult>;
+
+		using<TResource extends Disposable, T>(
+			resourceFactory: () => TResource,
+			enumerableFactory: (resource: TResource) => Enumerable<T>): Enumerable<T>;
+
+		catch<T>(...sources: Enumerable<T>[]): Enumerable<T>;
+		catchException<T>(...sources: Enumerable<T>[]): Enumerable<T>;
+
+		onErrorResumeNext<T>(...sources: Enumerable<T>[]): Enumerable<T>;
+
+		while<T>(condition: EnumerablePredicate<Enumerable<T>>, source: Enumerable<T>): Enumerable<T>;
+		whileDo<T>(condition: EnumerablePredicate<Enumerable<T>>, source: Enumerable<T>): Enumerable<T>;
+
+		if<T>(condition: () => boolean, thenSource: Enumerable<T>, elseSource?: Enumerable<T>): Enumerable<T>;
+		ifThen<T>(condition: () => boolean, thenSource: Enumerable<T>, elseSource?: Enumerable<T>): Enumerable<T>;
+
+		doWhile<T>(source: Enumerable<T>, condition: EnumerablePredicate<Enumerable<T>>): Enumerable<T>;
+
+		case<T>(selector: () => number, sources: { [key: number]: Enumerable<T>; }, defaultSource?: Enumerable<T>): Enumerable<T>;
+		case<T>(selector: () => string, sources: { [key: string]: Enumerable<T>; }, defaultSource?: Enumerable<T>): Enumerable<T>;
+		switchCase<T>(selector: () => number, sources: { [key: number]: Enumerable<T>; }, defaultSource?: Enumerable<T>): Enumerable<T>;
+		switchCase<T>(selector: () => string, sources: { [key: string]: Enumerable<T>; }, defaultSource?: Enumerable<T>): Enumerable<T>;
+
+		for<T, TResult>(source: Enumerable<T>, resultSelector: EnumerableFunc<T, TResult>): Enumerable<TResult>;
+		forIn<T, TResult>(source: Enumerable<T>, resultSelector: EnumerableFunc<T, TResult>): Enumerable<TResult>;
+	}
+}
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