fix(module): compare position value to mapped offset value (#64)

Position value was never compared against the mapped offset value. Instead, it was being compared against the initial offset value (if any). Therfore, mapped values never closed the animation loop as they never got satisfied by the animation stop method.

This fixes #62

src/app/+home/home.component.html

@@ -1,7 +1,10 @@
 <button
   (click)="show()"
-  [ngx-scroll-to-duration]="4000"
+  [ngx-scroll-to-duration]="1500"
   [ngx-scroll-to]="'destination'"
+  [ngx-scroll-to-offset]="-10"
+  [ngx-scroll-to-offset-map]="offsetMap"
+  [ngx-scroll-to-easing]="'easeInOutQuint'"
   >Go</button>
 <section *ngIf="visible" id="destination">
   You've reached your destination.

src/app/+home/home.component.scss

@@ -1,3 +1,7 @@
 button {
   margin-bottom: 100vh;
 }
+
+#destination {
+  margin-bottom: 200vh;
+}

src/app/+home/home.component.ts

@@ -8,8 +8,13 @@ import { Component, OnInit } from '@angular/core';
 export class HomeComponent implements OnInit {
 
   public visible = false;
+  public offsetMap;
 
-  constructor() { }
+  constructor() {
+    this.offsetMap = new Map();
+    this.offsetMap
+      .set(600, -500);
+  }
 
   ngOnInit() {
   }

src/app/modules/scroll-to/statics/scroll-to-animation.ts

@@ -57,6 +57,11 @@ export class ScrollToAnimation {
    */
   private _windowScrollTop: number;
 
+  /**
+   * Mapped Offset taken from the active Offset Map.
+   */
+  private _mappedOffset: number;
+
   /**
    * Class Constructor.
    *
@@ -90,17 +95,17 @@ export class ScrollToAnimation {
     const directionalDistance = this._startPosition - this._to;
     this._distance = Math.abs(this._startPosition - this._to);
 
-    let offset = this._options.offset;
+    this._mappedOffset = this._options.offset;
 
     // Set offset from Offset Map
     if (this._isBrowser) {
 
       this._options
         .offsetMap
-        .forEach((value, key) => offset = window.innerWidth > key ? value : offset);
+        .forEach((value, key) => this._mappedOffset = window.innerWidth > key ? value : this._mappedOffset);
     }
 
-    this._distance += offset * (directionalDistance <= 0 ? 1 : -1);
+    this._distance += this._mappedOffset * (directionalDistance <= 0 ? 1 : -1);
     this._source$ = new ReplaySubject();
   }
 
@@ -121,6 +126,7 @@ export class ScrollToAnimation {
    * @returns           Void
    */
   private _loop = (): void => {
+
     this._timeLapsed += this._tick;
     this._percentage = (this._timeLapsed / this._options.duration);
     this._percentage = (this._percentage > 1) ? 1 : this._percentage;
@@ -147,8 +153,8 @@ export class ScrollToAnimation {
     const currPosition = this._isWindow ? this._windowScrollTop : this._container.scrollTop;
 
     if (force
-      || Math.trunc(this._position) === (this._to + this._options.offset)
-      || currPosition === (this._to + this._options.offset)) {
+      || Math.trunc(this._position) === (this._to + this._mappedOffset)
+      || currPosition === (this._to + this._mappedOffset)) {
       clearInterval(this._interval);
       this._interval = null;
       this._source$.complete();