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Getting error on vis js events

I'm building a timeline in vue.js app so I decided to use vis.js but I'm having problems with it when I want to add some events. First of all when i set #drop="myDropCallback()" and when I drop one item nothing happens so the function is not called but when i put #mouseOver="myDropCallback()" then it works, its strange.
Second when I'm doing the mouseOver event I want to get the event properties with this.$refs.timeline.getEventProperties(event) but I'm getting this error every time
Error in event handler for "click": "TypeError: Cannot read property 'center' of undefined"
and this error
Cannot read property 'center' of undefined
So does anyone know how to fix that? Or am I doing something wrong?
Template
<timeline v-if="items.length > 0" ref="timeline"
:items="items"
:groups="groups"
:options="options"
#drop="myDropCallback()">
</timeline>
Drop function
myDropCallback: function (event) {
console.log('value', this.$refs.timeline.getEventProperties())
},
Picture of timeline

Here's an excerpt from the vis.js source. You'll notice that the first thing it tries to do is to find the event's center value.
Timeline.prototype.getEventProperties = function (event) {
var clientX = event.center ? event.center.x : event.clientX;
var clientY = event.center ? event.center.y : event.clientY;
var x;
if (this.options.rtl) {
x = util.getAbsoluteRight(this.dom.centerContainer) - clientX;
} else {
x = clientX - util.getAbsoluteLeft(this.dom.centerContainer);
}
var y = clientY - util.getAbsoluteTop(this.dom.centerContainer);
var item = this.itemSet.itemFromTarget(event);
var group = this.itemSet.groupFromTarget(event);
var customTime = CustomTime.customTimeFromTarget(event);
var snap = this.itemSet.options.snap || null;
var scale = this.body.util.getScale();
var step = this.body.util.getStep();
var time = this._toTime(x);
var snappedTime = snap ? snap(time, scale, step) : time;
var element = util.getTarget(event);
var what = null;
if (item != null) {
what = 'item';
} else if (customTime != null) {
what = 'custom-time';
} else if (util.hasParent(element, this.timeAxis.dom.foreground)) {
what = 'axis';
} else if (this.timeAxis2 && util.hasParent(element, this.timeAxis2.dom.foreground)) {
what = 'axis';
} else if (util.hasParent(element, this.itemSet.dom.labelSet)) {
what = 'group-label';
} else if (util.hasParent(element, this.currentTime.bar)) {
what = 'current-time';
} else if (util.hasParent(element, this.dom.center)) {
what = 'background';
}
return {
event: event,
item: item ? item.id : null,
group: group ? group.groupId : null,
what: what,
pageX: event.srcEvent ? event.srcEvent.pageX : event.pageX,
pageY: event.srcEvent ? event.srcEvent.pageY : event.pageY,
x: x,
y: y,
time: time,
snappedTime: snappedTime
};
};
So your issue is most likely due to not giving the method a valid event. I believe that this is because you aren't supplying any parameters to the getEventProperties method. I would try something like:
myDropCallback: function (event) {
console.log('value', this.$refs.timeline.getEventProperties(event))
},
Also, here is a good stack overflow post answered by one of the authors of vis.js: vis.js timeline how to add mouse over event to vis-item box-box

How to change the cursor on hover in openlayers 3?

I managed to add interactivity to a feature layer added from a remote GeoJSON resource. When I click on a feature I get its ID, fire an AJAX request and display some relevant info about the feature, on the page outside of the map area.
I used a Select interaction.
I would like to make it even clearer to the user that he can click on the features on the map. Is there any way I can change the mouse cursor to "cursor" of "hand" when the mouse hovers a feature contained in a ol.layer.Vector ?
I couldn't find anything in the doc, on this site or by googling.

It can be done as well without jQuery:
map.on("pointermove", function (evt) {
var hit = this.forEachFeatureAtPixel(evt.pixel, function(feature, layer) {
return true;
});
if (hit) {
this.getTargetElement().style.cursor = 'pointer';
} else {
this.getTargetElement().style.cursor = '';
}
});

Here is another way to do it:
map.on('pointermove', function(e){
var pixel = map.getEventPixel(e.originalEvent);
var hit = map.hasFeatureAtPixel(pixel);
map.getViewport().style.cursor = hit ? 'pointer' : '';
});

If that doesn't work, try a combination of the 2, seemed to work for my vector popup...
var target = map.getTarget();
var jTarget = typeof target === "string" ? $("#" + target) : $(target);
// change mouse cursor when over marker
$(map.getViewport()).on('mousemove', function (e) {
var pixel = map.getEventPixel(e.originalEvent);
var hit = map.forEachFeatureAtPixel(pixel, function (feature, layer) {
return true;
});
if (hit) {
jTarget.css("cursor", "pointer");
} else {
jTarget.css("cursor", "");
}
});

Thanks to the example link provided by Azathoth in the comments I worked a solution out:
using OL3 pointermove event
using jQuery to get the target element and change its cursor style
Here is the code :
var cursorHoverStyle = "pointer";
var target = map.getTarget();
//target returned might be the DOM element or the ID of this element dependeing on how the map was initialized
//either way get a jQuery object for it
var jTarget = typeof target === "string" ? $("#"+target) : $(target);
map.on("pointermove", function (event) {
var mouseCoordInMapPixels = [event.originalEvent.offsetX, event.originalEvent.offsetY];
//detect feature at mouse coords
var hit = map.forEachFeatureAtPixel(mouseCoordInMapPixels, function (feature, layer) {
return true;
});
if (hit) {
jTarget.css("cursor", cursorHoverStyle);
} else {
jTarget.css("cursor", "");
}
});
Here is the link to the example on OpenLayers site : http://openlayers.org/en/v3.0.0/examples/icon.html

For me it worked like this:
map.on('pointermove', function(e) {
if (e.dragging) return;
var pixel = e.map.getEventPixel(e.originalEvent);
var hit = e.map.forEachFeatureAtPixel(pixel, function (feature, layer) {
return true;
});
e.map.getTargetElement().style.cursor = hit ? 'pointer' : '';
});
I also added a layer filter:
map.on('pointermove', function(e) {
if (e.dragging) return;
var pixel = e.map.getEventPixel(e.originalEvent);
var hit = e.map.forEachFeatureAtPixel(pixel, function (feature, layer) {
return layer.get('name') === 'myLayer';
});
e.map.getTargetElement().style.cursor = hit ? 'pointer' : '';
});
I had to select a new solution as the old one I had use for the layer filter before did not work anymore:
var hit = e.map.hasFeatureAtPixel(e.pixel, function(layer){
return layer.get('name') === 'myLayer';
});

I did it with the following code:
var target = $(map.getTargetElement()); //getTargetElement is experimental as of 01.10.2015
map.on('pointermove', function (evt) {
if (map.hasFeatureAtPixel(evt.pixel)) { //hasFeatureAtPixel is experimental as of 01.10.2015
target.css('cursor', 'pointer');
} else {
target.css('cursor', '');
}
});

Another way (combined from parts of above answers, but even simpler):
map.on("pointermove", function (evt) {
var hit = map.hasFeatureAtPixel(evt.pixel);
map.getTargetElement().style.cursor = (hit ? 'pointer' : '');
});

Uncaught TypeError: Cannot set property 'cursor' of undefined.
Fixed with: map.getTargetElement()s.style.cursor = hit ? 'pointer' : ''; instead of map.getTarget().style.cursor = hit ? 'pointer' : '';

Simple way to get target element
var target = map.getTarget();
target = typeof target === "string" ?
document.getElementById(target) : target;
target.style.cursor = features.length > 0) ? 'pointer' : '';

If you guys are using Angular 2 you must use the following code:
this.map.on("pointermove", function (evt) {
var hit = evt.map.hasFeatureAtPixel(evt.pixel);
this.getTargetElement().style.cursor = hit ? 'pointer' : '';
});
If the map variable is a member class you refer to it as "this.map", instead if it is declared inside the current function it can be refered to as "map". But above all, you don't write
map.getTargetElement()
but you write
this.getTargetElement()

I tried to minimize pointermove event closure, by avoiding to update style when not necessary, because it calls so very often:
Example-1: uses jQuery:
var cursorStyle = "";
map.on("pointermove", function (e) {
let newStyle = this.hasFeatureAtPixel(e.pixel) ? "pointer" : "";
newStyle !== cursorStyle && $(this.getTargetElement()).css("cursor", cursorStyle = newStyle);
});
Example-2: no jQuery:
var cursorStyle = "";
map.on("pointermove", function (e) {
let newStyle = this.hasFeatureAtPixel(e.pixel) ? "pointer" : "";
if (newStyle !== cursorStyle) {
this.getTargetElement().style.cursor = cursorStyle = newStyle;
}
});

Easy way
map.on('pointermove', (e) => {
const pixel = map.getEventPixel(e.originalEvent);
const hit = map.hasFeatureAtPixel(pixel);
document.getElementById('map').style.cursor = hit ? 'pointer' : '';
});
}

How can I make window.showmodaldialog work in chrome 37?

We have a huge web application where we use window.showmodaldialog for alerts, confirmations and popups. Since Chrome version 37 this call has been disabled.
Is there any quick workaround to make window.showmodaldialog work in the latest version of Chrome?
I am adding here a workaround for window.showmodaldialog, although this is not a perfect workaround because this will not break the code execution as showmodaldialog was doing, instead this will open the popups.
window.showModalDialog = function (url, arg, feature) {
var opFeature = feature.split(";");
var featuresArray = new Array()
if (document.all) {
for (var i = 0; i < opFeature.length - 1; i++) {
var f = opFeature[i].split("=");
featuresArray[f[0]] = f[1];
}
}
else {
for (var i = 0; i < opFeature.length - 1; i++) {
var f = opFeature[i].split(":");
featuresArray[f[0].toString().trim().toLowerCase()] = f[1].toString().trim();
}
}
var h = "200px", w = "400px", l = "100px", t = "100px", r = "yes", c = "yes", s = "no";
if (featuresArray["dialogheight"]) h = featuresArray["dialogheight"];
if (featuresArray["dialogwidth"]) w = featuresArray["dialogwidth"];
if (featuresArray["dialogleft"]) l = featuresArray["dialogleft"];
if (featuresArray["dialogtop"]) t = featuresArray["dialogtop"];
if (featuresArray["resizable"]) r = featuresArray["resizable"];
if (featuresArray["center"]) c = featuresArray["center"];
if (featuresArray["status"]) s = featuresArray["status"];
var modelFeature = "height = " + h + ",width = " + w + ",left=" + l + ",top=" + t + ",model=yes,alwaysRaised=yes" + ",resizable= " + r + ",celter=" + c + ",status=" + s;
var model = window.open(url, "", modelFeature, null);
model.dialogArguments = arg;
}
Just put this code in the head section of page.

I put the following javascript in the page header and it seems to work. It detects when the browser does not support showModalDialog and attaches a custom method that uses window.open, parses the dialog specs (height, width, scroll, etc.), centers on opener and sets focus back to the window (if focus is lost). Also, it uses the URL as the window name so that a new window is not opened each time. If you are passing window args to the modal you will need to write some additional code to fix that. The popup is not modal but at least you don't have to change a lot of code. Might need some work for your circumstances.
<script type="text/javascript">
// fix for deprecated method in Chrome 37
if (!window.showModalDialog) {
window.showModalDialog = function (arg1, arg2, arg3) {
var w;
var h;
var resizable = "no";
var scroll = "no";
var status = "no";
// get the modal specs
var mdattrs = arg3.split(";");
for (i = 0; i < mdattrs.length; i++) {
var mdattr = mdattrs[i].split(":");
var n = mdattr[0];
var v = mdattr[1];
if (n) { n = n.trim().toLowerCase(); }
if (v) { v = v.trim().toLowerCase(); }
if (n == "dialogheight") {
h = v.replace("px", "");
} else if (n == "dialogwidth") {
w = v.replace("px", "");
} else if (n == "resizable") {
resizable = v;
} else if (n == "scroll") {
scroll = v;
} else if (n == "status") {
status = v;
}
}
var left = window.screenX + (window.outerWidth / 2) - (w / 2);
var top = window.screenY + (window.outerHeight / 2) - (h / 2);
var targetWin = window.open(arg1, arg1, 'toolbar=no, location=no, directories=no, status=' + status + ', menubar=no, scrollbars=' + scroll + ', resizable=' + resizable + ', copyhistory=no, width=' + w + ', height=' + h + ', top=' + top + ', left=' + left);
targetWin.focus();
};
}
</script>

From http://codecorner.galanter.net/2014/09/02/reenable-showmodaldialog-in-chrome/
It's deprecated by design. You can re-enable showModalDialog support, but only temporarily – until May of 2015. Use this time to create alternative solutions.
Here’s how to do it in Chrome for Windows. Open Registry Editor (regedit) and create following key:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome\EnableDeprecatedWebPlatformFeatures
Under the EnableDeprecatedWebPlatformFeatures key create a string value with name 1 and value of ShowModalDialog_EffectiveUntil20150430. To verify that the policy is enabled, visit chrome://policy URL.
UPDATE: If the above didn’t work for you here’s another method to try.
Download Chrome ADM templates from http://www.chromium.org/administrators/policy-templates
Extract and import policy relevant to your locale (e.g. windows\adm\en-US\chrome.adm. You can import either via gpedit.mscor using these utilities on Home editions of windows: http://blogs.technet.com/b/fdcc/archive/2008/05/07/lgpo-utilities.aspx)
Under “Adminstrative Templates” locate Google Chrome template and enable “Enable Deprecated Web Platform Feautes”.
Open the feature and add “ShowModalDialog_EffectiveUntil20150430″ key.

A very good, and working, javascript solution is provided here :
https://github.com/niutech/showModalDialog
I personnally used it, works like before for other browser and it creates a new dialog for chrome browser.
Here is an example on how to use it :
function handleReturnValue(returnValue) {
if (returnValue !== undefined) {
// do what you want
}
}
var myCallback = function (returnValue) { // callback for chrome usage
handleReturnValue(returnValue);
};
var returnValue = window.showModalDialog('someUrl', 'someDialogTitle', 'someDialogParams', myCallback);
handleReturnValue(returnValue); // for other browsers except Chrome

This article (Why is window.showModalDialog deprecated? What to use instead?) seems to suggest that showModalDialog has been deprecated.

The window.returnValue property does not work directly when you are opening a window using window.open() while it does work when you are using window.showModalDialog()
So in your case you have two options to achieve what you are trying to do.
Option 1 - Using window.showModalDialog()
In your parent page
var answer = window.showModalDialog(<your page and other arguments>)
if (answer == 1)
{ do some thing with answer }
and inside your child page you can make use of the window.returnValue directly like
window.returnValue = 'value that you want to return';
showModalDialog halts the executions of the JavaScript until the dialog box is closed and can get a return value from the opened dialog box when its closing.But the problem with showModalDialog is that it is not supported on many modern browsers. In contrast window.open just opens a window asynchronously (User can access both the parent window and the opened window). And the JavaScript execution will continue immediately. Which bring us to Option 2
Option 2 - Using window.open()
In your parent page write a function that deals with opening of your dialog.
function openDialog(url, width, height, callback){
if(window.showModalDialog){
options = 'dialogHeight: '+ height + '; dialogWidth: '+ width + '; scroll=no'
var returnValue = window.showModalDialog(url,this,options);
callback(returnValue)
}
else {
options ='toolbar=no, directories=no, location=no, status=yes, menubar=no, resizable=yes, scrollbars=no, width=' + width + ', height=' + height;
var childWindow = window.open(url,"",options);
$(childWindow).on('unload',function(){
if (childWindow.isOpened == null) {
childWindow.isOpened = 1;
}
else {
if(callback){
callback(childWindow.returnValue);
}
}
});
}
}
And whenever you want to use open a dialog. Write a callback that deals with the return value and pass it as a parameter to openDialog function
function callback(returnValue){
if(returnValue){
do something nice with the returnValue
}}
And when calling the function
openDialog(<your page>, 'width px', 'height px', callbak);
Check out an article on how to replace window.showModalDialog with window.open

I wouldn't try to temporarily enable a deprecated feature. According to the MDN documentation for showModalDialog, there's already a polyfill available on Github.
I just used that to add windows.showModalDialog to a legacy enterprise application as a userscript, but you can obviously also add it in the head of the HTML if you have access to the source.

I use a polyfill that seem to do a good job.
https://github.com/niutech/showModalDialog
http://niutech.github.io/showModalDialog/demo.html

Create a cross browser ModalDialog
function _showModalDialog(url, width, height, closeCallback) {
var modalDiv,
dialogPrefix = window.showModalDialog ? 'dialog' : '',
unit = 'px',
maximized = width === true || height === true,
w = width || 600,
h = height || 500,
border = 5,
taskbar = 40, // windows taskbar
header = 20,
x,
y;
if (maximized) {
x = 0;
y = 0;
w = screen.width;
h = screen.height;
} else {
x = window.screenX + (screen.width / 2) - (w / 2) - (border * 2);
y = window.screenY + (screen.height / 2) - (h / 2) - taskbar - border;
}
var features = [
'toolbar=no',
'location=no',
'directories=no',
'status=no',
'menubar=no',
'scrollbars=no',
'resizable=no',
'copyhistory=no',
'center=yes',
dialogPrefix + 'width=' + w + unit,
dialogPrefix + 'height=' + h + unit,
dialogPrefix + 'top=' + y + unit,
dialogPrefix + 'left=' + x + unit
],
showModal = function (context) {
if (context) {
modalDiv = context.document.createElement('div');
modalDiv.style.cssText = 'top:0;right:0;bottom:0;left:0;position:absolute;z-index:50000;';
modalDiv.onclick = function () {
if (context.focus) {
context.focus();
}
return false;
}
window.top.document.body.appendChild(modalDiv);
}
},
removeModal = function () {
if (modalDiv) {
modalDiv.onclick = null;
modalDiv.parentNode.removeChild(modalDiv);
modalDiv = null;
}
};
// IE
if (window.showModalDialog) {
window.showModalDialog(url, null, features.join(';') + ';');
if (closeCallback) {
closeCallback();
}
// Other browsers
} else {
var win = window.open(url, '', features.join(','));
if (maximized) {
win.moveTo(0, 0);
}
// When charging the window.
var onLoadFn = function () {
showModal(this);
},
// When you close the window.
unLoadFn = function () {
window.clearInterval(interval);
if (closeCallback) {
closeCallback();
}
removeModal();
},
// When you refresh the context that caught the window.
beforeUnloadAndCloseFn = function () {
try {
unLoadFn();
}
finally {
win.close();
}
};
if (win) {
// Create a task to check if the window was closed.
var interval = window.setInterval(function () {
try {
if (win == null || win.closed) {
unLoadFn();
}
} catch (e) { }
}, 500);
if (win.addEventListener) {
win.addEventListener('load', onLoadFn, false);
} else {
win.attachEvent('load', onLoadFn);
}
window.addEventListener('beforeunload', beforeUnloadAndCloseFn, false);
}
}
}

(function() {
window.spawn = window.spawn || function(gen) {
function continuer(verb, arg) {
var result;
try {
result = generator[verb](arg);
} catch (err) {
return Promise.reject(err);
}
if (result.done) {
return result.value;
} else {
return Promise.resolve(result.value).then(onFulfilled, onRejected);
}
}
var generator = gen();
var onFulfilled = continuer.bind(continuer, 'next');
var onRejected = continuer.bind(continuer, 'throw');
return onFulfilled();
};
window.showModalDialog = window.showModalDialog || function(url, arg, opt) {
url = url || ''; //URL of a dialog
arg = arg || null; //arguments to a dialog
opt = opt || 'dialogWidth:300px;dialogHeight:200px'; //options: dialogTop;dialogLeft;dialogWidth;dialogHeight or CSS styles
var caller = showModalDialog.caller.toString();
var dialog = document.body.appendChild(document.createElement('dialog'));
dialog.setAttribute('style', opt.replace(/dialog/gi, ''));
dialog.innerHTML = '×<iframe id="dialog-body" src="' + url + '" style="border: 0; width: 100%; height: 100%;"></iframe>';
document.getElementById('dialog-body').contentWindow.dialogArguments = arg;
document.getElementById('dialog-close').addEventListener('click', function(e) {
e.preventDefault();
dialog.close();
});
dialog.showModal();
//if using yield
if(caller.indexOf('yield') >= 0) {
return new Promise(function(resolve, reject) {
dialog.addEventListener('close', function() {
var returnValue = document.getElementById('dialog-body').contentWindow.returnValue;
document.body.removeChild(dialog);
resolve(returnValue);
});
});
}
//if using eval
var isNext = false;
var nextStmts = caller.split('\n').filter(function(stmt) {
if(isNext || stmt.indexOf('showModalDialog(') >= 0)
return isNext = true;
return false;
});
dialog.addEventListener('close', function() {
var returnValue = document.getElementById('dialog-body').contentWindow.returnValue;
document.body.removeChild(dialog);
nextStmts[0] = nextStmts[0].replace(/(window\.)?showModalDialog\(.*\)/g, JSON.stringify(returnValue));
eval('{\n' + nextStmts.join('\n'));
});
throw 'Execution stopped until showModalDialog is closed';
};
})()
;
**Explanation:
------------**
The best way to deal with showModalDialog for older application conversions is use to `https://github.com/niutech/showModalDialog` inorder to work with show modal dialogs and if modal dailog has ajax calls you need to create object and set the parameters of function to object and pass below...before that check for browser and set the useragent...example: agentStr = navigator.userAgent; and then check for chrome
var objAcceptReject={}; // create empty object and set the parameters to object and send to the other functions as dialog when opened in chrome breaks the functionality
function rejectClick(index, transferId) {
objAcceptReject.index=index;
objAcceptReject.transferId=transferId;
agentStr = navigator.userAgent;
var msie = ua.indexOf("MSIE ");
if (msie > 0) // If Internet Explorer, return version number
{
var ret = window.showModalDialog("/abc.jsp?accept=false",window,"dialogHeight:175px;dialogWidth:475px;scroll:no;status:no;help:no");
if (ret=="true") {
doSomeClick(index);
}
} else if ((agentStr.indexOf("Chrome")) >- 1){
spawn(function() {
var ret = window.showModalDialog("/abcd.jsp?accept=false",window,"dialogHeight:175px;dialogWidth:475px;scroll:no;status:no;help:no");
if (ret=="true") {// create an object and store values in objects and send as parameters
doSomeClick(objAcceptReject.index);
}
});
}
else {
var ret = window.showModalDialog("/xtz.jsp?accept=false",window,"dialogHeight:175px;dialogWidth:475px;scroll:no;status:no;help:no");
if (ret=="true") {
doSomeClick(index);
}
}

The window.showModalDialog is deprecated (Intent to Remove:
window.showModalDialog(), Removing showModalDialog from the Web
platform). [...]The latest plan is to land the showModalDialog removal
in Chromium 37. This means the feature will be gone in Opera 24 and
Chrome 37, both of which should be released in September.[...]

Yes, It's deprecated. Spent yesterday rewriting code to use Window.open and PostMessage instead.

Extend Zepto.js with a jQuery method? scrollTop()

I'm using Zepto.js on a current project. Zepto doesn't support the scrollTop() method that jQuery has in it.
Is it possible to kind of extend Zepto to work with scrollTop() too?
Update: All I want is to create my own small and simple "animated scroll" function like I have used before with jQuery. See the working example here. However I have no idea how to make the same function work without the scrollTop() function available in Zepto.js.

scrollTop isn't animatable using Zepto's .animate method, as it uses CSS transitions.
Try something like this: http://jsfiddle.net/DVDLM/5/
function scroll(scrollTo, time) {
var scrollFrom = parseInt(document.body.scrollTop),
i = 0,
runEvery = 5; // run every 5ms
scrollTo = parseInt(scrollTo);
time /= runEvery;
var interval = setInterval(function () {
i++;
document.body.scrollTop = (scrollTo - scrollFrom) / time * i + scrollFrom;
if (i >= time) {
clearInterval(interval);
}
}, runEvery);
}
$('#trigger').click(function () {
scroll('600px', 500);
});
EDIT: I added a runEvery variable, which specifies how often the interval should be ran. The lower this is, the smoother the animation is, but it could affect performance.
EDIT2: I think I misread the question. Here is the answer to the new question:
$.zepto.scrollTop = function (pixels) {
this[0].scrollTop = pixels;
};

dont want to steel nobody work so here is the short answer
Porting from jQuery to Zepto

Use the DOM native scrollTop property:
$('#el')[0].scrollTop = 0;

(function ($) {
['width', 'height'].forEach(function(dimension) {
var offset, Dimension = dimension.replace(/./, function(m) { return m[0].toUpperCase() });
$.fn['outer' + Dimension] = function(margin) {
var elem = this;
if (elem) {
var size = elem[dimension]();
var sides = {'width': ['left', 'right'], 'height': ['top', 'bottom']};
sides[dimension].forEach(function(side) {
if (margin) size += parseInt(elem.css('margin-' + side), 10);
});
return size;
}
else {
return null;
}
};
});
["Left", "Top"].forEach(function(name, i) {
var method = "scroll" + name;
function isWindow( obj ) {
return obj && typeof obj === "object" && "setInterval" in obj;
}
function getWindow( elem ) {
return isWindow( elem ) ? elem : elem.nodeType === 9 ? elem.defaultView || elem.parentWindow : false;
}
$.fn[method] = function( val ) {
var elem, win;
if (val === undefined) {
elem = this[0];
if (!elem) {
return null;
}
win = getWindow(elem);
// Return the scroll offset
return win ? ("pageXOffset" in win) ? win[i ? "pageYOffset" : "pageXOffset"] :
win.document.documentElement[method] ||
win.document.body[method] :
elem[method];
}
// Set the scroll offset
this.each(function() {
win = getWindow(this);
if (win) {
var xCoord = !i ? val : $(win).scrollLeft();
var yCoord = i ? val : $(win).scrollTop();
win.scrollTo(xCoord, yCoord);
}
else {
this[method] = val;
}
});
}
});
})(Zepto);

The answer is simple, Zepto dose not use timeout style animation, it uses css3, so here is a basic implementation for a scroll function:
HTML:
Animated Scroll
Hello You
​
CSS:
#page { height:5000px; position:relative; }
#element { position:absolute; top:600px }
JS:
function scroll(selector, animate, viewOffset) {
$('body').scrollToBottom (600, '800');
}
$('#trigger').click(function(e) {
e.preventDefault();
scroll( $('#element'), true, 30 );
});
$.fn.scrollToBottom = function(scrollHeight ,duration) {
var $el = this;
var el = $el[0];
var startPosition = el.scrollTop;
var delta = scrollHeight - startPosition;
var startTime = Date.now();
function scroll() {
var fraction = Math.min(1, (Date.now() - startTime) / duration);
el.scrollTop = delta * fraction + startPosition;
if(fraction < 1) {
setTimeout(scroll, 10);
}
}
scroll();
};
​

Note that version 1.0 of Zeptos now supports scrollTop(). See Documentation:
http://zeptojs.com/#scrollTop

Double tap on mobile safari

Is there a way to bind to a double-tap event (in a single line of code) for mobile safari? Or, the alternative is to implement it intercepting two single-tap events that happened in some short given time (example: http://appcropolis.com/blog/implementing-doubletap-on-iphones-and-ipads/)?

Short answer: you must implement via two clicks.
Actual answer: Here is a jQuery-free implementation of double-tap for mobile safari which only requires one line of code (to enable dblclick event):
https://gist.github.com/2927073
In addition, you will likely need to disable mobile Safari's default zoom with this meta tag:
<meta name="viewport" content="width=device-width,user-scalable=no" />

If you want to have working double click both on browser and IOS platform, you should have the following code:
jQuery.event.special.dblclick = {
setup: function(data, namespaces) {
var agent = navigator.userAgent.toLowerCase();
if (agent.indexOf('iphone') >= 0 || agent.indexOf('ipad') >= 0 || agent.indexOf('ipod') >= 0) {
var elem = this,
$elem = jQuery(elem);
$elem.bind('touchend.dblclick', jQuery.event.special.dblclick.handler);
} else {
var elem = this,
$elem = jQuery(elem);
$elem.bind('click.dblclick', jQuery.event.special.dblclick.handler);
}
},
teardown: function(namespaces) {
var agent = navigator.userAgent.toLowerCase();
if (agent.indexOf('iphone') >= 0 || agent.indexOf('ipad') >= 0 || agent.indexOf('ipod') >= 0) {
var elem = this,
$elem = jQuery(elem);
$elem.unbind('touchend.dblclick');
} else {
var elem = this,
$elem = jQuery(elem);
$elem.unbind('click.dblclick', jQuery.event.special.dblclick.handler);
}
},
handler: function(event) {
var elem = event.target,
$elem = jQuery(elem),
lastTouch = $elem.data('lastTouch') || 0,
now = new Date().getTime();
var delta = now - lastTouch;
if (delta > 20 && delta < 500) {
$elem.data('lastTouch', 0);
$elem.trigger('dblclick');
} else {
$elem.data('lastTouch', now);
}
}
};
Try it here:
http://jsfiddle.net/UXRF8/

Override dblclick event and use bind, live, on, delegate like for any other event:
jQuery.event.special.dblclick = {
setup: function(data, namespaces) {
var elem = this,
$elem = jQuery(elem);
$elem.bind('touchend.dblclick', jQuery.event.special.dblclick.handler);
},
teardown: function(namespaces) {
var elem = this,
$elem = jQuery(elem);
$elem.unbind('touchend.dblclick');
},
handler: function(event) {
var elem = event.target,
$elem = jQuery(elem),
lastTouch = $elem.data('lastTouch') || 0,
now = new Date().getTime();
var delta = now - lastTouch;
if(delta > 20 && delta<500){
$elem.data('lastTouch', 0);
$elem.trigger('dblclick');
}else
$elem.data('lastTouch', now);
}
};