[javascript] Smooth scroll to specific div on click

What I'm trying to do is make it so that if you click on a button, it scrolls down (smoothly) to a specific div on the page.

What I need is if you click on the button, it smooth scrolls to the div 'second'.

.first {_x000D_
    width: 100%;_x000D_
    height: 1000px;_x000D_
    background: #ccc;_x000D_
}_x000D_
_x000D_
.second {_x000D_
    width: 100%;_x000D_
    height: 1000px;_x000D_
    background: #999;_x000D_
}

<div class="first"><button type="button">Click Me!</button></div>_x000D_
<div class="second">Hi</div>

I took the Ned Rockson's version and adjusted it to allow upwards scrolls as well.

var smoothScroll = function(elementId) {
  var MIN_PIXELS_PER_STEP = 16;
  var MAX_SCROLL_STEPS = 30;
  var target = document.getElementById(elementId);
  var scrollContainer = target;
  do {
    scrollContainer = scrollContainer.parentNode;
    if (!scrollContainer) return;
    scrollContainer.scrollTop += 1;
  } while (scrollContainer.scrollTop === 0);

  var targetY = 0;
  do {
    if (target === scrollContainer) break;
    targetY += target.offsetTop;
  } while (target = target.offsetParent);

  var pixelsPerStep = Math.max(MIN_PIXELS_PER_STEP,
    Math.abs(targetY - scrollContainer.scrollTop) / MAX_SCROLL_STEPS);

  var isUp = targetY < scrollContainer.scrollTop;

  var stepFunc = function() {
    if (isUp) {
      scrollContainer.scrollTop = Math.max(targetY, scrollContainer.scrollTop - pixelsPerStep);
      if (scrollContainer.scrollTop <= targetY) {
        return;
      }
    } else {
        scrollContainer.scrollTop = Math.min(targetY, scrollContainer.scrollTop + pixelsPerStep);

      if (scrollContainer.scrollTop >= targetY) {
        return;
      }
    }

    window.requestAnimationFrame(stepFunc);
  };

  window.requestAnimationFrame(stepFunc);
};

What if u use scrollIntoView function?

var elmntToView = document.getElementById("sectionId");
elmntToView.scrollIntoView(); 

Has {behavior: "smooth"} too.... ;) https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView

I played around with nico's answer a little and it felt jumpy. Did a bit of investigation and found window.requestAnimationFrame which is a function that is called on each repaint cycle. This allows for a more clean-looking animation. Still trying to hone in on good default values for step size but for my example things look pretty good using this implementation.

var smoothScroll = function(elementId) {
    var MIN_PIXELS_PER_STEP = 16;
    var MAX_SCROLL_STEPS = 30;
    var target = document.getElementById(elementId);
    var scrollContainer = target;
    do {
        scrollContainer = scrollContainer.parentNode;
        if (!scrollContainer) return;
        scrollContainer.scrollTop += 1;
    } while (scrollContainer.scrollTop == 0);

    var targetY = 0;
    do {
        if (target == scrollContainer) break;
        targetY += target.offsetTop;
    } while (target = target.offsetParent);

    var pixelsPerStep = Math.max(MIN_PIXELS_PER_STEP,
                                 (targetY - scrollContainer.scrollTop) / MAX_SCROLL_STEPS);

    var stepFunc = function() {
        scrollContainer.scrollTop =
            Math.min(targetY, pixelsPerStep + scrollContainer.scrollTop);

        if (scrollContainer.scrollTop >= targetY) {
            return;
        }

        window.requestAnimationFrame(stepFunc);
    };

    window.requestAnimationFrame(stepFunc);
}

Ned Rockson basically answers this question. However there is a fatal flaw within his solution. When the targeted element is closer to the bottom of the page than the viewport-height, the function doesn't reach its exit statement and traps the user on the bottom of the page. This is simply solved by limiting the iteration count.

var smoothScroll = function(elementId) {
    var MIN_PIXELS_PER_STEP = 16;
    var MAX_SCROLL_STEPS = 30;
    var target = document.getElementById(elementId);
    var scrollContainer = target;
    do {
        scrollContainer = scrollContainer.parentNode;
        if (!scrollContainer) return;
        scrollContainer.scrollTop += 1;
    } while (scrollContainer.scrollTop == 0);

    var targetY = 0;
    do {
        if (target == scrollContainer) break;
        targetY += target.offsetTop;
    } while (target = target.offsetParent);

    var pixelsPerStep = Math.max(MIN_PIXELS_PER_STEP,
                                 (targetY - scrollContainer.scrollTop) / MAX_SCROLL_STEPS);

    var iterations = 0;
    var stepFunc = function() {
        if(iterations > MAX_SCROLL_STEPS){
            return;
        }
        scrollContainer.scrollTop =
            Math.min(targetY, pixelsPerStep + scrollContainer.scrollTop);

        if (scrollContainer.scrollTop >= targetY) {
            return;
        }

        window.requestAnimationFrame(stepFunc);
    };

    window.requestAnimationFrame(stepFunc);
}

You can use basic css to achieve smooth scroll

html {
  scroll-behavior: smooth;
}

There are many examples of smooth scrolling using JS libraries like jQuery, Mootools, Prototype, etc.

The following example is on pure JavaScript. If you have no jQuery/Mootools/Prototype on page or you don't want to overload page with heavy JS libraries the example will be of help.

http://jsfiddle.net/rjSfP/

HTML Part:

<div class="first"><button type="button" onclick="smoothScroll(document.getElementById('second'))">Click Me!</button></div>
<div class="second" id="second">Hi</div>

CSS Part:

.first {
    width: 100%;
    height: 1000px;
    background: #ccc;
}

.second {
    width: 100%;
    height: 1000px;
    background: #999;
}

JS Part:

window.smoothScroll = function(target) {
    var scrollContainer = target;
    do { //find scroll container
        scrollContainer = scrollContainer.parentNode;
        if (!scrollContainer) return;
        scrollContainer.scrollTop += 1;
    } while (scrollContainer.scrollTop == 0);

    var targetY = 0;
    do { //find the top of target relatively to the container
        if (target == scrollContainer) break;
        targetY += target.offsetTop;
    } while (target = target.offsetParent);

    scroll = function(c, a, b, i) {
        i++; if (i > 30) return;
        c.scrollTop = a + (b - a) / 30 * i;
        setTimeout(function(){ scroll(c, a, b, i); }, 20);
    }
    // start scrolling
    scroll(scrollContainer, scrollContainer.scrollTop, targetY, 0);
}