feat(web): document the API

lib/binding_web/src/lookahead_iterator.ts

@@ -8,29 +8,36 @@ export class LookaheadIterator implements Iterable<string> {
   /** @internal */
   private language: Language;
 
+  /** @internal */
   constructor(internal: Internal, address: number, language: Language) {
     assertInternal(internal);
     this[0] = address;
     this.language = language;
   }
 
+  /** Get the current symbol of the lookahead iterator. */
   get currentTypeId(): number {
     return C._ts_lookahead_iterator_current_symbol(this[0]);
   }
 
+  /** Get the current symbol name of the lookahead iterator. */
   get currentType(): string {
     return this.language.types[this.currentTypeId] || 'ERROR';
   }
 
+  /** Delete the lookahead iterator, freeing its resources. */
   delete(): void {
     C._ts_lookahead_iterator_delete(this[0]);
     this[0] = 0;
   }
 
-  resetState(stateId: number): boolean {
-    return Boolean(C._ts_lookahead_iterator_reset_state(this[0], stateId));
-  }
 
+  /**
+   * Reset the lookahead iterator.
+   *
+   * This returns `true` if the language was set successfully and `false`
+   * otherwise.
+   */
   reset(language: Language, stateId: number): boolean {
     if (C._ts_lookahead_iterator_reset(this[0], language[0], stateId)) {
       this.language = language;
@@ -39,6 +46,22 @@ export class LookaheadIterator implements Iterable<string> {
     return false;
   }
 
+  /**
+   * Reset the lookahead iterator to another state.
+   *
+   * This returns `true` if the iterator was reset to the given state and
+   * `false` otherwise.
+   */
+  resetState(stateId: number): boolean {
+    return Boolean(C._ts_lookahead_iterator_reset_state(this[0], stateId));
+  }
+
+  /**
+   * Returns an iterator that iterates over the symbols of the lookahead iterator.
+   *
+   * The iterator will yield the current symbol name as a string for each step
+   * until there are no more symbols to iterate over.
+   */
   [Symbol.iterator](): Iterator<string> {
     return {
       next: (): IteratorResult<string> => {