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zepto.js is a minimalist inlinable framework for mobile WebKit browsers, with a jQuery-like chaining syntax
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zepto.js - modular branch

This is a fork of Thomas Fuchs minimalistic JavaScript framework zepto.js.

It was based on a early stage of the framework but branched into a completely different direction, the core structure was totally refactored. It may have extra/missing features and/or different API than the original. The code structure/implementations are diverging from the original at each day.

To know more about why this branch was created and what should come next see this pull request.

The main idea is to keep the API as close as possible to jQuery without bloating the code size but focusing on the most important/used methods, features will be added as needed and will try to unit test 100% of the API.

Some changes implemented on this branch may be added to the main one but probably most of them won't.


This branch favors good practices and readability over file-size, specially since modern compressors/minifiers does a good job at reducing code size, for more details read: The Performance Dogma.


Modern mobile browsers.

Syntax & features

Basic call

$('some css selector').html('set contents').css('set styles');

Element functions

  • .each(fn) - Execute a function for each matched element.
  • .get() - Return array of all elements found.
  • .get(0) - Return first element found.
  • .eq(1) - Reduce matched elements to a single el0ement by index.
  • .find('selector') - Match descendant element(s) based on selector.
  • .html('new html') - Set the contents of the element(s).
  • .css('css properties') - Set styles of the element(s).
  • .append, prepend, after, before - Like html, but append/prepend to element contents or before/after element.
  • .transition(transform, opacity, duration, delay, ease) - Use -webkit-transform/opacity and do an animation.
  • .delegate(selector, eventType, handler) - Attach an Event listener to matched elements using the event delegation pattern.
  • .hasClass(className) - Check if any matched element has given class.
  • .addClass(className) - Add one or more classes (separated by spaces) into each matched element.
  • .removeClass(className) - Removes one or more class names (separated by spaces) from matched elements, removes all classes if null.
  • .toggleClass(className, switch) - Add or remove one or more classes from each element in the set of matched elements.
  • .add(elementsArray) - Add a set of elements to the matched elements set.
  • .map(callbackFn(i, element)) - Pass each element in the current matched set through a function, producing a new zepto object containing the return values.
  • .attr(name, value) - Set/get attribute value.


  • $.isDef(param) - Check if parameter is different than undefined.
  • $.isFunction(param) - Check if parameter is a Function.
  • $.isArray(param) - Check if parameter is an Array.
  • $.unique(array) - Return a new array that contain only unique items.
  • $.makeArray(obj) - Convert an array-like Object into an real array.
  • $.extend(firstObj, secondObj) - Mixin, copy properties from one object into another, will extend zepto by default if second parameter is omitted.
  • $.map(array, callbackFn) - Translate all items in an array or array-like object to another array of items. (similar to similar to and not to
  • $.each(collection, callbackFn(i|key, value)) - Call method over each array/object item.
  • $.noop - Empty function.
  • $.trim(str) - Remove white spaces from beginning and end of string.
  • $.ready(fn) - Specify a method to be called after DOM is "ready" (fully loaded).

Event Handlers


  • .bind(eventType, eventHandler) - Attach event listener onto each matched element.
  • .unbind(eventType, eventHandler) - Remove event listener from each matched element, (both parameters are required).
var handler = function(evt){
    $(this).unbind('touchstart', handler); //remove listener after first call, so it will be called only once per matched element

$('#my_div').bind('touchstart', handler); //add listener

delegate ("live" event)

.delegate(selector, eventType, eventHandler) - Listen for events triggered by descendant nodes of matched elements - A.K.A "event delegation".

//will trigger when any descendant element of "#my_div" that has the class ".touchable" is touched
$('#my_div').delegate('.touchable', 'touchstart', function(evt){
    alert("I'm touched!");



Custom "swipe" gesture event. (only works for touch enabled devices)

  • .swipe(directionStr, endCallbackFn, [thresholdObj], [preventScroll])
    • directionStr: 'up', 'down', 'left', 'right' - direction of swipe gesture.
    • endCallbackFn({direction: string, changeX: number, changeY: number}) - called on touch end if gesture matches threshold.
    • thresholdObj : {x: number, y:number} : defines how accurate the swipe gesture needs to be.
    • preventScroll : boolean - prevent browser scroll.


  • $.ajax(method, url, succesCallback, errorCallback)
  • $.get(url, succesCallback, errorCallback)
  • $.post(url, succesCallback, errorCallback)
  • $.getJSON(url, succesCallback, errorCallback)


Future improvements

  • Add sniffing based on feature detection, maybe only load zepto.min.js and subsequent files if browser support required features.


  • Make sure the site still works without JavaScript since many devices doesn't support it! Use it as an enhancement and not as a prerequisite.
  • Compress all your JavaScript files before deploying.

Unit Test

  • Tests may be created before features are implemented, so don't get scared if a few of them throws errors telling that method doesn't exist (unless method is described on the README file).
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