I am having trouble getting a smooth scroll service to work in angular 2. Are there any services for smooth scrolling, or plain anchor scrolling, that might work until the angular 2 team gets the $anchorScroll angular2 equivalent working?
So far I have just tried:
Setting *ngFor loop incremental id on a parent div
[attr.id]="'point' + i"
Calling a scrollto on a button with the id passed
<button
type="button"
class="btn btn-lg btn-default "
(click)="smoothScroll('point'+i)">
Scroll to point
</button>
And in the associated component I am trying to implement a plain js smooth scroll function
smoothScroll(eID) {
var startY = currentYPosition();
var stopY = elmYPosition(eID);
var distance = stopY > startY ? stopY - startY : startY - stopY;
if (distance < 100) {
scrollTo(0, stopY); return;
}
var speed = Math.round(distance / 100);
if (speed >= 20) speed = 20;
var step = Math.round(distance / 25);
var leapY = stopY > startY ? startY + step : startY - step;
var timer = 0;
if (stopY > startY) {
for (var i = startY; i < stopY; i += step) {
setTimeout(this.win.scrollTo(0, leapY), timer * speed);
leapY += step; if (leapY > stopY) leapY = stopY; timer++;
} return;
}
for (var i = startY; i > stopY; i -= step) {
setTimeout(this.win.scrollTo(0,leapY), timer * speed);
leapY -= step; if (leapY < stopY) leapY = stopY; timer++;
}
}
function currentYPosition() {
// Firefox, Chrome, Opera, Safari
if (self.pageYOffset) return self.pageYOffset;
// Internet Explorer 6 - standards mode
if (document.documentElement && document.documentElement.scrollTop)
return document.documentElement.scrollTop;
// Internet Explorer 6, 7 and 8
if (document.body.scrollTop) return document.body.scrollTop;
return 0;
}
function elmYPosition(eID) {
var elm = document.getElementById(eID);
var y = elm.offsetTop;
var node = elm;
while (node.offsetParent && node.offsetParent != document.body) {
node = node.offsetParent;
y += node.offsetTop;
} return y;
}
I'm also trying to give access to the window for the this._win.scrollTo which is coming from a window provider service
import {Injectable, Provider} from 'angular2/core';
import {window} from 'angular2/src/facade/browser';
import {unimplemented} from 'angular2/src/facade/exceptions';
function _window(): Window {
return window
}
export abstract class WINDOW {
get nativeWindow(): Window {
return unimplemented();
}
}
class WindowRef_ extends WINDOW {
constructor() {
super();
}
get nativeWindow(): Window {
return _window();
}
}
export const WINDOW_PROVIDERS = [
new Provider(WINDOW, { useClass: WindowRef_ }),
];
** EDIT ---------------------**
I changed the this.win.scrollTo to this.win.window.scrollTo and now I am getting an effect similar to angular1.x $anchorscroll where the scroll is a snappy just instead of a smooth transition, but the scroll is not smooth and I am getting the following exception error.
UPDATE
I am no longer getting that error after finding out that angular2 is doing the setTimeout a bit differently, but the scroll is still instantaneous and not a smooth scroll.
I changed
setTimeout(this.win.scrollTo(0, leapY), timer * speed);
to
setTimeout(() => this.win.scrollTo(0, leapY), timer * speed);
there is a method in the window
object called scrollTo()
.
If you set the behavior to 'smooth' the page will handle the smooth scroll.
example (scroll to top of page):
window.scrollTo({ left: 0, top: 0, behavior: 'smooth' });
And with fallback example:
try
{
window.scrollTo({ left: 0, top: 0, behavior: 'smooth' });
} catch (e) {
window.scrollTo(0, 0);
}