The Nextcloud JSLoader app enables admins to specify JavaScript which loads on each page in Nextcloud. In the spirit of the holidays we decided to use this for a little fun to show you what it can do. Let’s make it snow in Nextcloud!

A simple snow script

The JSLoader app allows the admin to include JavaScript into all Nextcloud pages. This can be used for web analytics for example, but of course – anything can be loaded and we’re looking for a wintery theme!

A quick search brought us to this nice snow script from Scott Schiller, who claims the script has been making it snow on the web since 2003. We’ll simply go ahead and load that script in the JSLoader on Nextcloud, after tuning some of its parameters!

Step 1

So first, install the JSLoader app in the app section and visit the admin configuration of this app:

Step 2

In the javascript input box you paste the following code:

/** @license
 * DHTML Snowstorm! JavaScript-based snow for web pages
 * Making it snow on the internets since 2003. You're welcome.
 * -----------------------------------------------------------
 * Version 1.44.20131208 (Previous rev: 1.44.20131125)
 * Copyright (c) 2007, Scott Schiller. All rights reserved.
 * Code provided under the BSD License
 * http://schillmania.com/projects/snowstorm/license.txt
 */
/*jslint nomen: true, plusplus: true, sloppy: true, vars: true, white: true */
/*global window, document, navigator, clearInterval, setInterval */

var snowStorm = (function(window, document) {

  // --- common properties ---

  this.autoStart = true;          // Whether the snow should start automatically or not.
  this.excludeMobile = true;      // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) Enable at your own risk.
  this.flakesMax = 128;           // Limit total amount of snow made (falling + sticking)
  this.flakesMaxActive = 64;      // Limit amount of snow falling at once (less = lower CPU use)
  this.animationInterval = 33;    // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
  this.useGPU = true;             // Enable transform-based hardware acceleration, reduce CPU load.
  this.className = null;          // CSS class name for further customization on snow elements
  this.excludeMobile = true;      // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) By default, be nice.
  this.flakeBottom = null;        // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
  this.followMouse = true;        // Snow movement can respond to the user's mouse
  this.snowColor = '#efefef';        // Don't eat (or use?) yellow snow.
  this.snowCharacter = '❄';  // • = bullet, · is square on some systems etc.
  this.snowStick = true;          // Whether or not snow should "stick" at the bottom. When off, will never collect.
  this.targetElement = null;      // element which snow will be appended to (null = document.body) - can be an element ID eg. 'myDiv', or a DOM node reference
  this.useMeltEffect = true;      // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
  this.useTwinkleEffect = true;  // Allow snow to randomly "flicker" in and out of view while falling
  this.usePositionFixed = false;  // true = snow does not shift vertically when scrolling. May increase CPU load, disabled by default - if enabled, used only where supported
  this.usePixelPosition = false;  // Whether to use pixel values for snow top/left vs. percentages. Auto-enabled if body is position:relative or targetElement is specified.

  // --- less-used bits ---

  this.freezeOnBlur = true;       // Only snow when the window is in focus (foreground.) Saves CPU.
  this.flakeLeftOffset = 0;       // Left margin/gutter space on edge of container (eg. browser window.) Bump up these values if seeing horizontal scrollbars.
  this.flakeRightOffset = 0;      // Right margin/gutter space on edge of container
  this.flakeWidth = 32;            // Max pixel width reserved for snow element
  this.flakeHeight = 32;           // Max pixel height reserved for snow element
  this.vMaxX = 5;                 // Maximum X velocity range for snow
  this.vMaxY = 4;                 // Maximum Y velocity range for snow
  this.zIndex = 5000;                // CSS stacking order applied to each snowflake

  // --- "No user-serviceable parts inside" past this point, yadda yadda ---

  var storm = this,
  features,
  // UA sniffing and backCompat rendering mode checks for fixed position, etc.
  isIE = navigator.userAgent.match(/msie/i),
  isIE6 = navigator.userAgent.match(/msie 6/i),
  isMobile = navigator.userAgent.match(/mobile|opera m(ob|in)/i),
  isBackCompatIE = (isIE && document.compatMode === 'BackCompat'),
  noFixed = (isBackCompatIE || isIE6),
  screenX = null, screenX2 = null, screenY = null, scrollY = null, docHeight = null, vRndX = null, vRndY = null,
  windOffset = 1,
  windMultiplier = 2,
  flakeTypes = 6,
  fixedForEverything = false,
  targetElementIsRelative = false,
  opacitySupported = (function(){
    try {
      document.createElement('div').style.opacity = '0.5';
    } catch(e) {
      return false;
    }
    return true;
  }()),
  didInit = false,
  docFrag = document.createDocumentFragment();

  features = (function() {

    var getAnimationFrame;

    /**
     * hat tip: paul irish
     * http://paulirish.com/2011/requestanimationframe-for-smart-animating/
     * https://gist.github.com/838785
     */

    function timeoutShim(callback) {
      window.setTimeout(callback, 1000/(storm.animationInterval || 20));
    }

    var _animationFrame = (window.requestAnimationFrame ||
        window.webkitRequestAnimationFrame ||
        window.mozRequestAnimationFrame ||
        window.oRequestAnimationFrame ||
        window.msRequestAnimationFrame ||
        timeoutShim);

    // apply to window, avoid "illegal invocation" errors in Chrome
    getAnimationFrame = _animationFrame ? function() {
      return _animationFrame.apply(window, arguments);
    } : null;

    var testDiv;

    testDiv = document.createElement('div');

    function has(prop) {

      // test for feature support
      var result = testDiv.style[prop];
      return (result !== undefined ? prop : null);

    }

    // note local scope.
    var localFeatures = {

      transform: {
        ie:  has('-ms-transform'),
        moz: has('MozTransform'),
        opera: has('OTransform'),
        webkit: has('webkitTransform'),
        w3: has('transform'),
        prop: null // the normalized property value
      },

      getAnimationFrame: getAnimationFrame

    };

    localFeatures.transform.prop = (
      localFeatures.transform.w3 || 
      localFeatures.transform.moz ||
      localFeatures.transform.webkit ||
      localFeatures.transform.ie ||
      localFeatures.transform.opera
    );

    testDiv = null;

    return localFeatures;

  }());

  this.timer = null;
  this.flakes = [];
  this.disabled = false;
  this.active = false;
  this.meltFrameCount = 20;
  this.meltFrames = [];

  this.setXY = function(o, x, y) {

    if (!o) {
      return false;
    }

    if (storm.usePixelPosition || targetElementIsRelative) {

      o.style.left = (x - storm.flakeWidth) + 'px';
      o.style.top = (y - storm.flakeHeight) + 'px';

    } else if (noFixed) {

      o.style.right = (100-(x/screenX*100)) + '%';
      // avoid creating vertical scrollbars
      o.style.top = (Math.min(y, docHeight-storm.flakeHeight)) + 'px';

    } else {

      if (!storm.flakeBottom) {

        // if not using a fixed bottom coordinate...
        o.style.right = (100-(x/screenX*100)) + '%';
        o.style.bottom = (100-(y/screenY*100)) + '%';

      } else {

        // absolute top.
        o.style.right = (100-(x/screenX*100)) + '%';
        o.style.top = (Math.min(y, docHeight-storm.flakeHeight)) + 'px';

      }

    }

  };

  this.events = (function() {

    var old = (!window.addEventListener && window.attachEvent), slice = Array.prototype.slice,
    evt = {
      add: (old?'attachEvent':'addEventListener'),
      remove: (old?'detachEvent':'removeEventListener')
    };

    function getArgs(oArgs) {
      var args = slice.call(oArgs), len = args.length;
      if (old) {
        args[1] = 'on' + args[1]; // prefix
        if (len > 3) {
          args.pop(); // no capture
        }
      } else if (len === 3) {
        args.push(false);
      }
      return args;
    }

    function apply(args, sType) {
      var element = args.shift(),
          method = [evt[sType]];
      if (old) {
        element[method](args[0], args[1]);
      } else {
        element[method].apply(element, args);
      }
    }

    function addEvent() {
      apply(getArgs(arguments), 'add');
    }

    function removeEvent() {
      apply(getArgs(arguments), 'remove');
    }

    return {
      add: addEvent,
      remove: removeEvent
    };

  }());

  function rnd(n,min) {
    if (isNaN(min)) {
      min = 0;
    }
    return (Math.random()*n)+min;
  }

  function plusMinus(n) {
    return (parseInt(rnd(2),10)===1?n*-1:n);
  }

  this.randomizeWind = function() {
    var i;
    vRndX = plusMinus(rnd(storm.vMaxX,0.2));
    vRndY = rnd(storm.vMaxY,0.2);
    if (this.flakes) {
      for (i=0; i<this.flakes.length; i++) {
        if (this.flakes[i].active) {
          this.flakes[i].setVelocities();
        }
      }
    }
  };

  this.scrollHandler = function() {
    var i;
    // "attach" snowflakes to bottom of window if no absolute bottom value was given
    scrollY = (storm.flakeBottom ? 0 : parseInt(window.scrollY || document.documentElement.scrollTop || (noFixed ? document.body.scrollTop : 0), 10));
    if (isNaN(scrollY)) {
      scrollY = 0; // Netscape 6 scroll fix
    }
    if (!fixedForEverything && !storm.flakeBottom && storm.flakes) {
      for (i=0; i<storm.flakes.length; i++) {
        if (storm.flakes[i].active === 0) {
          storm.flakes[i].stick();
        }
      }
    }
  };

  this.resizeHandler = function() {
    if (window.innerWidth || window.innerHeight) {
      screenX = window.innerWidth - 16 - storm.flakeRightOffset;
      screenY = (storm.flakeBottom || window.innerHeight);
    } else {
      screenX = (document.documentElement.clientWidth || document.body.clientWidth || document.body.scrollWidth) - (!isIE ? 8 : 0) - storm.flakeRightOffset;
      screenY = storm.flakeBottom || document.documentElement.clientHeight || document.body.clientHeight || document.body.scrollHeight;
    }
    docHeight = document.body.offsetHeight;
    screenX2 = parseInt(screenX/2,10);
  };

  this.resizeHandlerAlt = function() {
    screenX = storm.targetElement.offsetWidth - storm.flakeRightOffset;
    screenY = storm.flakeBottom || storm.targetElement.offsetHeight;
    screenX2 = parseInt(screenX/2,10);
    docHeight = document.body.offsetHeight;
  };

  this.freeze = function() {
    // pause animation
    if (!storm.disabled) {
      storm.disabled = 1;
    } else {
      return false;
    }
    storm.timer = null;
  };

  this.resume = function() {
    if (storm.disabled) {
       storm.disabled = 0;
    } else {
      return false;
    }
    storm.timerInit();
  };

  this.toggleSnow = function() {
    if (!storm.flakes.length) {
      // first run
      storm.start();
    } else {
      storm.active = !storm.active;
      if (storm.active) {
        storm.show();
        storm.resume();
      } else {
        storm.stop();
        storm.freeze();
      }
    }
  };

  this.stop = function() {
    var i;
    this.freeze();
    for (i=0; i<this.flakes.length; i++) {
      this.flakes[i].o.style.display = 'none';
    }
    storm.events.remove(window,'scroll',storm.scrollHandler);
    storm.events.remove(window,'resize',storm.resizeHandler);
    if (storm.freezeOnBlur) {
      if (isIE) {
        storm.events.remove(document,'focusout',storm.freeze);
        storm.events.remove(document,'focusin',storm.resume);
      } else {
        storm.events.remove(window,'blur',storm.freeze);
        storm.events.remove(window,'focus',storm.resume);
      }
    }
  };

  this.show = function() {
    var i;
    for (i=0; i<this.flakes.length; i++) {
      this.flakes[i].o.style.display = 'block';
    }
  };

  this.SnowFlake = function(type,x,y) {
    var s = this;
    this.type = type;
    this.x = x||parseInt(rnd(screenX-20),10);
    this.y = (!isNaN(y)?y:-rnd(screenY)-12);
    this.vX = null;
    this.vY = null;
    this.vAmpTypes = [1,1.2,1.4,1.6,1.8]; // "amplification" for vX/vY (based on flake size/type)
    this.vAmp = this.vAmpTypes[this.type] || 1;
    this.melting = false;
    this.meltFrameCount = storm.meltFrameCount;
    this.meltFrames = storm.meltFrames;
    this.meltFrame = 0;
    this.twinkleFrame = 0;
    this.active = 1;
    this.fontSize = (10+(this.type/5)*10);
    this.o = document.createElement('div');
    this.o.innerHTML = storm.snowCharacter;
    if (storm.className) {
      this.o.setAttribute('class', storm.className);
    }
    this.o.style.color = storm.snowColor;
    this.o.style.position = (fixedForEverything?'fixed':'absolute');
    if (storm.useGPU && features.transform.prop) {
      // GPU-accelerated snow.
      this.o.style[features.transform.prop] = 'translate3d(0px, 0px, 0px)';
    }
    this.o.style.width = storm.flakeWidth+'px';
    this.o.style.height = storm.flakeHeight+'px';
    this.o.style.fontFamily = 'arial,verdana';
    this.o.style.cursor = 'default';
    this.o.style.overflow = 'hidden';
    this.o.style.fontWeight = 'normal';
    this.o.style.zIndex = storm.zIndex;
    docFrag.appendChild(this.o);

    this.refresh = function() {
      if (isNaN(s.x) || isNaN(s.y)) {
        // safety check
        return false;
      }
      storm.setXY(s.o, s.x, s.y);
    };

    this.stick = function() {
      if (noFixed || (storm.targetElement !== document.documentElement && storm.targetElement !== document.body)) {
        s.o.style.top = (screenY+scrollY-storm.flakeHeight)+'px';
      } else if (storm.flakeBottom) {
        s.o.style.top = storm.flakeBottom+'px';
      } else {
        s.o.style.display = 'none';
        s.o.style.bottom = '0%';
        s.o.style.position = 'fixed';
        s.o.style.display = 'block';
      }
    };

    this.vCheck = function() {
      if (s.vX>=0 && s.vX<0.2) {
        s.vX = 0.2;
      } else if (s.vX<0 && s.vX>-0.2) {
        s.vX = -0.2;
      }
      if (s.vY>=0 && s.vY<0.2) {
        s.vY = 0.2;
      }
    };

    this.move = function() {
      var vX = s.vX*windOffset, yDiff;
      s.x += vX;
      s.y += (s.vY*s.vAmp);
      if (s.x >= screenX || screenX-s.x < storm.flakeWidth) { // X-axis scroll check
        s.x = 0;
      } else if (vX < 0 && s.x-storm.flakeLeftOffset < -storm.flakeWidth) {
        s.x = screenX-storm.flakeWidth-1; // flakeWidth;
      }
      s.refresh();
      yDiff = screenY+scrollY-s.y+storm.flakeHeight;
      if (yDiff<storm.flakeHeight) {
        s.active = 0;
        if (storm.snowStick) {
          s.stick();
        } else {
          s.recycle();
        }
      } else {
        if (storm.useMeltEffect && s.active && s.type < 3 && !s.melting && Math.random()>0.998) {
          // ~1/1000 chance of melting mid-air, with each frame
          s.melting = true;
          s.melt();
          // only incrementally melt one frame
          // s.melting = false;
        }
        if (storm.useTwinkleEffect) {
          if (s.twinkleFrame < 0) {
            if (Math.random() > 0.97) {
              s.twinkleFrame = parseInt(Math.random() * 8, 10);
            }
          } else {
            s.twinkleFrame--;
            if (!opacitySupported) {
              s.o.style.visibility = (s.twinkleFrame && s.twinkleFrame % 2 === 0 ? 'hidden' : 'visible');
            } else {
              s.o.style.opacity = (s.twinkleFrame && s.twinkleFrame % 2 === 0 ? 0 : 1);
            }
          }
        }
      }
    };

    this.animate = function() {
      // main animation loop
      // move, check status, die etc.
      s.move();
    };

    this.setVelocities = function() {
      s.vX = vRndX+rnd(storm.vMaxX*0.12,0.1);
      s.vY = vRndY+rnd(storm.vMaxY*0.12,0.1);
    };

    this.setOpacity = function(o,opacity) {
      if (!opacitySupported) {
        return false;
      }
      o.style.opacity = opacity;
    };

    this.melt = function() {
      if (!storm.useMeltEffect || !s.melting) {
        s.recycle();
      } else {
        if (s.meltFrame < s.meltFrameCount) {
          s.setOpacity(s.o,s.meltFrames[s.meltFrame]);
          s.o.style.fontSize = s.fontSize-(s.fontSize*(s.meltFrame/s.meltFrameCount))+'px';
          s.o.style.lineHeight = storm.flakeHeight+2+(storm.flakeHeight*0.75*(s.meltFrame/s.meltFrameCount))+'px';
          s.meltFrame++;
        } else {
          s.recycle();
        }
      }
    };

    this.recycle = function() {
      s.o.style.display = 'none';
      s.o.style.position = (fixedForEverything?'fixed':'absolute');
      s.o.style.bottom = 'auto';
      s.setVelocities();
      s.vCheck();
      s.meltFrame = 0;
      s.melting = false;
      s.setOpacity(s.o,1);
      s.o.style.padding = '0px';
      s.o.style.margin = '0px';
      s.o.style.fontSize = s.fontSize+'px';
      s.o.style.lineHeight = (storm.flakeHeight+2)+'px';
      s.o.style.textAlign = 'center';
      s.o.style.verticalAlign = 'baseline';
      s.x = parseInt(rnd(screenX-storm.flakeWidth-20),10);
      s.y = parseInt(rnd(screenY)*-1,10)-storm.flakeHeight;
      s.refresh();
      s.o.style.display = 'block';
      s.active = 1;
    };

    this.recycle(); // set up x/y coords etc.
    this.refresh();

  };

  this.snow = function() {
    var active = 0, flake = null, i, j;
    for (i=0, j=storm.flakes.length; i<j; i++) {
      if (storm.flakes[i].active === 1) {
        storm.flakes[i].move();
        active++;
      }
      if (storm.flakes[i].melting) {
        storm.flakes[i].melt();
      }
    }
    if (active<storm.flakesMaxActive) {
      flake = storm.flakes[parseInt(rnd(storm.flakes.length),10)];
      if (flake.active === 0) {
        flake.melting = true;
      }
    }
    if (storm.timer) {
      features.getAnimationFrame(storm.snow);
    }
  };

  this.mouseMove = function(e) {
    if (!storm.followMouse) {
      return true;
    }
    var x = parseInt(e.clientX,10);
    if (x<screenX2) {
      windOffset = -windMultiplier+(x/screenX2*windMultiplier);
    } else {
      x -= screenX2;
      windOffset = (x/screenX2)*windMultiplier;
    }
  };

  this.createSnow = function(limit,allowInactive) {
    var i;
    for (i=0; i<limit; i++) {
      storm.flakes[storm.flakes.length] = new storm.SnowFlake(parseInt(rnd(flakeTypes),10));
      if (allowInactive || i>storm.flakesMaxActive) {
        storm.flakes[storm.flakes.length-1].active = -1;
      }
    }
    storm.targetElement.appendChild(docFrag);
  };

  this.timerInit = function() {
    storm.timer = true;
    storm.snow();
  };

  this.init = function() {
    var i;
    for (i=0; i<storm.meltFrameCount; i++) {
      storm.meltFrames.push(1-(i/storm.meltFrameCount));
    }
    storm.randomizeWind();
    storm.createSnow(storm.flakesMax); // create initial batch
    storm.events.add(window,'resize',storm.resizeHandler);
    storm.events.add(window,'scroll',storm.scrollHandler);
    if (storm.freezeOnBlur) {
      if (isIE) {
        storm.events.add(document,'focusout',storm.freeze);
        storm.events.add(document,'focusin',storm.resume);
      } else {
        storm.events.add(window,'blur',storm.freeze);
        storm.events.add(window,'focus',storm.resume);
      }
    }
    storm.resizeHandler();
    storm.scrollHandler();
    if (storm.followMouse) {
      storm.events.add(isIE?document:window,'mousemove',storm.mouseMove);
    }
    storm.animationInterval = Math.max(20,storm.animationInterval);
    storm.timerInit();
  };

  this.start = function(bFromOnLoad) {
    if (!didInit) {
      didInit = true;
    } else if (bFromOnLoad) {
      // already loaded and running
      return true;
    }
    if (typeof storm.targetElement === 'string') {
      var targetID = storm.targetElement;
      storm.targetElement = document.getElementById(targetID);
      if (!storm.targetElement) {
        throw new Error('Snowstorm: Unable to get targetElement "'+targetID+'"');
      }
    }
    if (!storm.targetElement) {
      storm.targetElement = (document.body || document.documentElement);
    }
    if (storm.targetElement !== document.documentElement && storm.targetElement !== document.body) {
      // re-map handler to get element instead of screen dimensions
      storm.resizeHandler = storm.resizeHandlerAlt;
      //and force-enable pixel positioning
      storm.usePixelPosition = true;
    }
    storm.resizeHandler(); // get bounding box elements
    storm.usePositionFixed = (storm.usePositionFixed && !noFixed && !storm.flakeBottom); // whether or not position:fixed is to be used
    if (window.getComputedStyle) {
      // attempt to determine if body or user-specified snow parent element is relatlively-positioned.
      try {
        targetElementIsRelative = (window.getComputedStyle(storm.targetElement, null).getPropertyValue('position') === 'relative');
      } catch(e) {
        // oh well
        targetElementIsRelative = false;
      }
    }
    fixedForEverything = storm.usePositionFixed;
    if (screenX && screenY && !storm.disabled) {
      storm.init();
      storm.active = true;
    }
  };

  function doDelayedStart() {
    window.setTimeout(function() {
      storm.start(true);
    }, 20);
    // event cleanup
    storm.events.remove(isIE?document:window,'mousemove',doDelayedStart);
  }

  function doStart() {
    if (!storm.excludeMobile || !isMobile) {
      doDelayedStart();
    }
    // event cleanup
    storm.events.remove(window, 'load', doStart);
  }

  // hooks for starting the snow
  if (storm.autoStart) {
    storm.events.add(window, 'load', doStart, false);
  }

  return this;

}(window, document));

Step 3

After pasting, click outside the box to let Nextcloud fill in the CSP text and click save.

Now, open a new window in anonymous browsing mode and check the result! You can of course modify the whole design of your Nextcloud easily using the built-in theming…

Tuning

There are a few parameters to tune here:

• We replaced the default dot with a snow emoji, setting this.snowCharacter = '❄';
• Increased the size of flakes to max 32×32 pixels (flakeWidth and flakeHeight)
• Setting this.snowColor = '#efefef'; will make the snow a little more visible on the largely white background of Nextcloud.
• To make sure the snow shows up over the UI within Nextcloud, we set this.zIndex = 5000; – if you don’t modify this, you won’t see snow during normal Nextcloud use, only on the login screen.
  Various other values can ensure the snow does or doesn’t go over certain items. For example, with a value of 1000 it won’t cover the top bar, but only the content in the window.

Ending the year

We’re now nearing the end of the year for most of us. We released Nextcloud 15 and activities are winding down! For those coming to the 35th installment of the Chaos Communication Congress in Germany in the days before December 31st, we’ll be there with an assembly and several talks and workshops! If you can’t make it there, we hope to see you next year at enterprise events like CS3, the Univention summit or Didacta, or community events like FOSDEM or SCALE in the first quarter of the year. Then there are of course our Enterprise Day in March or the Nextcloud Conference 2019 (date to be announced), perfect opportunities to dive deeper in Nextcloud.

We wish you all happy holidays and a great new year!