Smooth scroll angular2

Question

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

Answer 1

Thanks to the accepted answer I was able to implement a smooth "scroll to top". Scrolling to the top is actually even easier than scrolling to a particular target element since we are scrolling to the 0-position always. Here is the code:

scrollTo(yPoint: number, duration: number) {
    setTimeout(() => {
        window.scrollTo(0, yPoint)
    }, duration);
    return;
}

smoothScrollToTop() {
    let startY = this.currentYPosition();
    let stopY = 0; // window top
    let distance = stopY > startY ? stopY - startY : startY - stopY;
    if (distance < 100) {
        window.scrollTo(0, stopY);
        return;
    }
    let speed = Math.round(distance / 100);
    let step = speed;
    speed = Math.max(9, speed); //min 9 otherwise it won't look smooth
    let leapY = stopY > startY ? startY + step : startY - step;
    let timer = 0;
    if (stopY > startY) {
        for (let i = startY; i < stopY; i += step) {
            // since setTimeout is asynchronous, the for-loop will will fire all scrolls
            // nearly simoultaniously. Therefore, we need to multiply the speed with
            // a counter which lets the scrolls start with a growing offset which lets the
            // setTimeout wait for a growing time till it scrolls there
            // that way, we prevent the window to scroll instantly to the target Yposition
            this.scrollTo(leapY, timer * speed);
            leapY += step; if (leapY > stopY) leapY = stopY; timer++;
        }
        return;
    } else {
        for (let i = startY; i > stopY; i -= step) {
            this.scrollTo(leapY, timer * speed);
            leapY -= step; if (leapY < stopY) leapY = stopY; timer++;
        }
    }
}

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;
}

If you want, you can let your "Scroll-To-Top" button appear dynamically when user scrolls:

@HostListener('window:scroll', ['$event'])
onWindowScroll(event) {
    this.onScrollFadeInOutScrollToTopButton();
}

shouldShowScrollToTop: boolean = false;

onScrollFadeInOutScrollToTopButton() {
    this.shouldShowScrollToTop = (window.pageYOffset >= window.screen.height/2);
}

And the HTML for the Scroll-to-top Button:

^

As you can see, that button also has an animation trigger. You can think about using an icon for the button and ideally, your button should have a position:fixed; style.