HashSet and Dictionary in TypeScript: export of Interface -

i think need feedback on collection classes - still learning typescript , javascript , these implementations can surely improved. looking forward suggestion. think use generic types in useful way, advice here appreciated.

the answer looking removing duplicate ihashtable definition end of both snippets , moving own file, cannot done seems. unsure if interface in first place. compiles , works way, far can see.

the collection types incomplete , define basic function @ moment. once sure use language , features correct other functions should not difficult.

here hashset:

import { ihashable } "./ihashable"  export class hashset<t extends ihashable> {     private _items: hashtable<t>;      public constructor() {         this._items = {};     }      public add(key: t): void {         let str: string = key.gethash();         if (this._items[str] == null) {             this._items[str] = key;         }         else {             throw new rangeerror("key '" + str + "' exists.");         }     }      public contains(key: t): boolean {         let str: string = key.gethash();         return this._items[str] != null;     } }  interface hashtable<t> {     [key: string]: t; } 

i wonder if can avoid checking-before-adding in way. javascript-dictionary relies on allow duplicates, avoid them there no other way check myself?

this dictionary:

import { ihashable } "./ihashable"  export class dictionary<t1 extends ihashable, t2> {     private _items: hashtable<keyvaluepair<t1, t2>>;      public constructor() {         this._items = {};     }      public add(key: t1, value: t2) {         let str: string = key.gethash();         if (this._items[str] == null) {             let kvp: keyvaluepair<t1, t2> = new keyvaluepair(key, value);             this._items[str] = kvp;         }         else {             throw new rangeerror("key '" + str + "' exists.");         }     }      public containskey(key: t1): boolean {         let str: string = key.gethash();         return this._items[str] != null;     }      public get(key: t1): t2 {         let str: string = key.gethash();         let kvp: keyvaluepair<t1, t2> = this._items[str];         if (kvp == null) throw new rangeerror("key '" + str + "' not found")         return kvp.value;     } }  export class keyvaluepair<t1 extends ihashable, t2> {     private _key: t1;     private _value: t2;      public key(): t1 { return this._key; }     public value(): t2 { return this._value; }      public constructor(key: t1, value: t2) {         this._key = key;         this._value = value;     } }  interface hashtable<t> {     [key: string]: t; } 

both rely on definition of ihashable (hashable , hashtable: should find other names.)

export interface ihashable {     gethash(): string; } 

the dictionary looks bit strange, "wraps" dictionary new type keyvaluepair , uses in javascript dictionary. hope gain doing own type key, in , out, long offers string can indexed. - no idea if makes sense or completly wrong.

what missing count of items in collection, way remove items, , way iterate on keys , values. regarding iterating on post question implementation of list , foreach on it, hoping iterating keys or values might possible in same way.

probably important question forgot here: how gethash-method build own class? going have static number on classes, , count 1 in constructor before assign number each instance. guarantee uniqueness... there better?

thanks tip! ralf