You Don't Need jQuery

Frontend environments evolve rapidly nowadays, modern browsers have already implemented a great deal of DOM/BOM APIs which are good enough. We don't have to learn jQuery from scratch for DOM manipulation or events. In the meantime, thanks to the prevailment of frontend libraries such as React, Angular and Vue, manipulating DOM directly becomes anti-pattern, jQuery has never been less important. This project summarizes most of the jQuery method alternatives in native implementation, with IE 10+ support.

Translations
Query Selector
CSS & Style
DOM Manipulation
Ajax
Events
Utilities
Promises
Animation
Alternatives
Browser Support

Translations

Query Selector

In place of common selectors like class, id or attribute we can use document.querySelector or document.querySelectorAll for substitution. The differences lie in:

document.querySelector returns the first matched element
document.querySelectorAll returns all matched elements as NodeList. It can be converted to Array using Array.prototype.slice.call(document.querySelectorAll(selector));
If there are no elements matched, jQuery and document.querySelectorAll will return [], whereas document.querySelector will return null.

Notice: document.querySelector and document.querySelectorAll are quite SLOW, try to use document.getElementById, document.getElementsByClassName or document.getElementsByTagName if you want to get a performance bonus.

1.0 Query by selector

// jQuery
$('selector');

// Native
document.querySelectorAll('selector');

1.1 Query by class

// jQuery
$('.class');

// Native
document.querySelectorAll('.class');

// or
document.getElementsByClassName('class');

1.2 Query by id

// jQuery
$('#id');

// Native
document.querySelector('#id');

// or
document.getElementById('id');

1.3 Query by attribute

// jQuery
$('a[target=_blank]');

// Native
document.querySelectorAll('a[target=_blank]');

1.4 Query in descendents

// jQuery
$el.find('li');

// Native
el.querySelectorAll('li');

1.5 Sibling/Previous/Next Elements

Sibling elements

// jQuery
$el.siblings();

// Native
Array.prototype.filter.call(el.parentNode.children, (child) =>
  child !== el
);

Previous elements

// jQuery
$el.prev();

// Native
el.previousElementSibling;

Next elements

// jQuery
$el.next();

// Native
el.nextElementSibling;

1.6 Closest

Return the first matched element by provided selector, traversing from current element to document.

// jQuery
$el.closest(selector);

// Native - Only latest, NO IE
el.closest(selector);

// Native - IE10+
function closest(el, selector) {
  const matchesSelector = el.matches || el.webkitMatchesSelector || el.mozMatchesSelector || el.msMatchesSelector;

  while (el) {
    if (matchesSelector.call(el, selector)) {
      return el;
    } else {
      el = el.parentElement;
    }
  }
  return null;
}

1.7 Parents Until

Get the ancestors of each element in the current set of matched elements, up to but not including the element matched by the selector, DOM node, or jQuery object.

// jQuery
$el.parentsUntil(selector, filter);

// Native
function parentsUntil(el, selector, filter) {
  const result = [];
  const matchesSelector = el.matches || el.webkitMatchesSelector || el.mozMatchesSelector || el.msMatchesSelector;

  // match start from parent
  el = el.parentElement;
  while (el && !matchesSelector.call(el, selector)) {
    if (!filter) {
      result.push(el);
    } else {
      if (matchesSelector.call(el, filter)) {
        result.push(el);
      }
    }
    el = el.parentElement;
  }
  return result;
}

1.8 Form

Input/Textarea

// jQuery
$('#my-input').val();

// Native
document.querySelector('#my-input').value;

Get index of e.currentTarget between .radio

// jQuery
$('.radio').index(e.currentTarget);

// Native
Array.prototype.indexOf.call(document.querySelectorAll('.radio'), e.currentTarget);

1.9 Iframe Contents

$('iframe').contents() returns contentDocument for this specific iframe

Iframe contents

// jQuery
$iframe.contents();

// Native
iframe.contentDocument;

Iframe Query

// jQuery
$iframe.contents().find('.css');

// Native
iframe.contentDocument.querySelectorAll('.css');

1.10 Get body

// jQuery
$('body');

// Native
document.body;

1.11 Attribute getter and setter

Get an attribute

// jQuery
$el.attr('foo');

// Native
el.getAttribute('foo');

Set an attribute

// jQuery, note that this works in memory without change the DOM
$el.attr('foo', 'bar');

// Native
el.setAttribute('foo', 'bar');

Get a data- attribute

// jQuery
$el.data('foo');

// Native (use `getAttribute`)
el.getAttribute('data-foo');

// Native (use `dataset` if only need to support IE 11+)
el.dataset['foo'];

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CSS & Style

2.1 CSS

Get style

// jQuery
$el.css('color');

// Native
// NOTE: Known bug, will return 'auto' if style value is 'auto'
const win = el.ownerDocument.defaultView;

// null means not to return pseudo styles
win.getComputedStyle(el, null).color;

Set style

// jQuery
$el.css({ color: '#f01' });

// Native
el.style.color = '#f01';

Get/Set Styles

Note that if you want to set multiple styles once, you could refer to setStyles method in oui-dom-utils package.

Add class

// jQuery
$el.addClass(className);

// Native
el.classList.add(className);

Remove class

// jQuery
$el.removeClass(className);

// Native
el.classList.remove(className);

has class

// jQuery
$el.hasClass(className);

// Native
el.classList.contains(className);

Toggle class

// jQuery
$el.toggleClass(className);

// Native
el.classList.toggle(className);

2.2 Width & Height

Width and Height are theoretically identical, take Height as example:

Window height

// window height
$(window).height();

// with scrollbar
window.document.documentElement.clientHeight;

// without scrollbar, behaves like jQuery
window.innerHeight;

Document height

// jQuery
$(document).height();

// Native
const body = document.body;
const html = document.documentElement;
const height = Math.max(
  body.offsetHeight,
  body.scrollHeight,
  html.clientHeight,
  html.offsetHeight,
  html.scrollHeight
);

Element height

// jQuery
$el.height();

// Native
function getHeight(el) {
  const styles = window.getComputedStyle(el);
  const height = el.offsetHeight;
  const borderTopWidth = parseFloat(styles.borderTopWidth);
  const borderBottomWidth = parseFloat(styles.borderBottomWidth);
  const paddingTop = parseFloat(styles.paddingTop);
  const paddingBottom = parseFloat(styles.paddingBottom);
  return height - borderBottomWidth - borderTopWidth - paddingTop - paddingBottom;
}

// accurate to integer（when `border-box`, it's `height - border`; when `content-box`, it's `height + padding`）
el.clientHeight;

// accurate to decimal（when `border-box`, it's `height`; when `content-box`, it's `height + padding + border`）
el.getBoundingClientRect().height;

2.3 Position & Offset

Position

Get the current coordinates of the element relative to the offset parent.

// jQuery
$el.position();

// Native
{ left: el.offsetLeft, top: el.offsetTop }

Offset

Get the current coordinates of the element relative to the document.

// jQuery
$el.offset();

// Native
function getOffset (el) {
  const box = el.getBoundingClientRect();

  return {
    top: box.top + window.pageYOffset - document.documentElement.clientTop,
    left: box.left + window.pageXOffset - document.documentElement.clientLeft
  };
}

2.4 Scroll Top

Get the current vertical position of the scroll bar for the element.

// jQuery
$(window).scrollTop();

// Native
(document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;

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DOM Manipulation

3.1 Remove

Remove the element from the DOM.

// jQuery
$el.remove();

// Native
el.parentNode.removeChild(el);

3.2 Text
- Get text
  
  Get the combined text contents of the element including their descendants,
```
// jQuery
$el.text();

// Native
el.textContent;
```
- Set text
  
  Set the content of the element to the specified text.
```
// jQuery
$el.text(string);

// Native
el.textContent = string;
```

3.3 HTML

Get HTML

// jQuery
$el.html();

// Native
el.innerHTML;

Set HTML

// jQuery
$el.html(htmlString);

// Native
el.innerHTML = htmlString;

3.4 Append

Append child element after the last child of parent element

// jQuery
$el.append('<div id="container">Hello World</div>');

// Native (HTML string)
el.insertAdjacentHTML('beforeend', '<div id="container">Hello World</div>');

// Native (Element)
el.appendChild(newEl);

3.5 Prepend

// jQuery
$el.prepend('<div id="container">Hello World</div>');

// Native (HTML string)
el.insertAdjacentHTML('afterbegin', '<div id="container">Hello World</div>');

// Native (Element)
el.insertBefore(newEl, el.firstChild);

3.6 insertBefore

Insert a new node before the selected elements

// jQuery
$newEl.insertBefore(selector);

// Native (HTML string)
el.insertAdjacentHTML('beforebegin ', '<div id="container">Hello World</div>');

// Native (Element)
const el = document.querySelector(selector);
if (el.parentNode) {
  el.parentNode.insertBefore(newEl, el);
}

3.7 insertAfter

Insert a new node after the selected elements

// jQuery
$newEl.insertAfter(selector);

// Native (HTML string)
el.insertAdjacentHTML('afterend', '<div id="container">Hello World</div>');

// Native (Element)
const el = document.querySelector(selector);
if (el.parentNode) {
  el.parentNode.insertBefore(newEl, el.nextSibling);
}

3.8 is

Return true if it matches the query selector

// jQuery - Notice `is` also work with `function` or `elements` which is not concerned here
$el.is(selector);

// Native
el.matches(selector);

3.9 clone

Create a deep copy of that element

// jQuery
$el.clone();

// Native
el.cloneNode();

// For Deep clone , set param as `true`

3.10 empty

Remove all child nodes

// jQuery
$el.empty();

// Native
el.innerHTML = '';

3.11 wrap

Wrap an HTML structure around each element

// jQuery
$('.inner').wrap('<div class="wrapper"></div>');

// Native
Array.prototype.forEach.call(document.querySelectorAll('.inner'), (el) => {
  const wrapper = document.createElement('div');
  wrapper.className = 'wrapper';
  el.parentNode.insertBefore(wrapper, el);
  el.parentNode.removeChild(el);
  wrapper.appendChild(el);
});

3.12 unwrap

Remove the parents of the set of matched elements from the DOM

// jQuery
$('.inner').unwrap();

// Native
Array.prototype.forEach.call(document.querySelectorAll('.inner'), (el) => {
  Array.prototype.forEach.call(el.childNodes, (child) => {
    el.parentNode.insertBefore(child, el);
  });
  el.parentNode.removeChild(el);
});

3.13 replaceWith

Replace each element in the set of matched elements with the provided new content

// jQuery
$('.inner').replaceWith('<div class="outer"></div>');

// Native
Array.prototype.forEach.call(document.querySelectorAll('.inner'), (el) => {
  const outer = document.createElement('div');
  outer.className = 'outer';
  el.parentNode.insertBefore(outer, el);
  el.parentNode.removeChild(el);
});

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Ajax

Fetch API is the new standard to replace XMLHttpRequest to do ajax. It works on Chrome and Firefox, you can use polyfills to make it work on legacy browsers.

Try github/fetch on IE9+ or fetch-ie8 on IE8+, fetch-jsonp to make JSONP requests.

4.1 Load data from the server and place the returned HTML into the matched element.

// jQuery
$(selector).load(url, completeCallback)

// Native
fetch(url).then(data => data.text()).then(data => {
  document.querySelector(selector).innerHTML = data
}).then(completeCallback)

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Events

For a complete replacement with namespace and delegation, refer to https://github.com/oneuijs/oui-dom-events

5.0 Document ready by DOMContentLoaded

// jQuery
$(document).ready(eventHandler);

// Native
// Check if the DOMContentLoaded has already been completed
if (document.readyState === 'complete' || document.readyState !== 'loading') {
  eventHandler();
} else {
  document.addEventListener('DOMContentLoaded', eventHandler);
}

5.1 Bind an event with on

// jQuery
$el.on(eventName, eventHandler);

// Native
el.addEventListener(eventName, eventHandler);

5.2 Unbind an event with off

// jQuery
$el.off(eventName, eventHandler);

// Native
el.removeEventListener(eventName, eventHandler);

5.3 Trigger

// jQuery
$(el).trigger('custom-event', {key1: 'data'});

// Native
if (window.CustomEvent) {
  const event = new CustomEvent('custom-event', {detail: {key1: 'data'}});
} else {
  const event = document.createEvent('CustomEvent');
  event.initCustomEvent('custom-event', true, true, {key1: 'data'});
}

el.dispatchEvent(event);

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Utilities

Most of utilities are found by native API. Others advanced functions could be choosed better utilities library focus on consistency and performance. Recommend lodash to replace.

6.1 Basic utilities

isArray

Determine whether the argument is an array.

// jQuery
$.isArray(array);

// Native
Array.isArray(array);

isWindow

Determine whether the argument is a window.

// jQuery
$.isWindow(obj);

// Native
function isWindow(obj) {
  return obj !== null && obj !== undefined && obj === obj.window;
}

inArray

Search for a specified value within an array and return its index (or -1 if not found).

// jQuery
$.inArray(item, array);

// Native
array.indexOf(item) > -1;

// ES6-way
array.includes(item);

isNumeric

Determine if the argument passed is numerical. Use typeof to decide the type or the type example for better accuracy.

// jQuery
$.isNumeric(item);

// Native
function isNumeric(value) {
  var type = typeof value;

  return (type === 'number' || type === 'string') && !Number.isNaN(value - Number.parseFloat(value));
}

isFunction

Determine if the argument passed is a JavaScript function object.

// jQuery
$.isFunction(item);

// Native
function isFunction(item) {
  if (typeof item === 'function') {
    return true;
  }
  var type = Object.prototype.toString(item);
  return type === '[object Function]' || type === '[object GeneratorFunction]';
}

isEmptyObject

Check to see if an object is empty (contains no enumerable properties).

// jQuery
$.isEmptyObject(obj);

// Native
function isEmptyObject(obj) {
  return Object.keys(obj).length === 0;
}

isPlainObject

Check to see if an object is a plain object (created using “{}” or “new Object”).

// jQuery
$.isPlainObject(obj);

// Native
function isPlainObject(obj) {
  if (typeof (obj) !== 'object' || obj.nodeType || obj !== null && obj !== undefined && obj === obj.window) {
    return false;
  }

  if (obj.constructor &&
      !Object.prototype.hasOwnProperty.call(obj.constructor.prototype, 'isPrototypeOf')) {
    return false;
  }

  return true;
}

extend

Merge the contents of two or more objects together into the first object. object.assign is ES6 API, and you could use polyfill also.

// jQuery
$.extend({}, defaultOpts, opts);

// Native
Object.assign({}, defaultOpts, opts);

trim

Remove the white-space from the beginning and end of a string.

// jQuery
$.trim(string);

// Native
string.trim();

Translate all items in an array or object to new array of items.

// jQuery
$.map(array, (value, index) => {
});

// Native
array.map((value, index) => {
});

each

A generic iterator function, which can be used to seamlessly iterate over both objects and arrays.

// jQuery
$.each(array, (index, value) => {
});

// Native
array.forEach((value, index) => {
});

grep

Finds the elements of an array which satisfy a filter function.

// jQuery
$.grep(array, (value, index) => {
});

// Native
array.filter((value, index) => {
});

type

Determine the internal JavaScript [Class] of an object.

// jQuery
$.type(obj);

// Native
function type(item) {
  const reTypeOf = /(?:^\[object\s(.*?)\]$)/;
  return Object.prototype.toString.call(item)
    .replace(reTypeOf, '$1')
    .toLowerCase();
}

merge

Merge the contents of two arrays together into the first array.

// jQuery
$.merge(array1, array2);

// Native
// But concat function doesn't remove duplicate items.
function merge(...args) {
  return [].concat(...args)
}

Return a number representing the current time.

// jQuery
$.now();

// Native
Date.now();

proxy

Takes a function and returns a new one that will always have a particular context.

// jQuery
$.proxy(fn, context);

// Native
fn.bind(context);

makeArray

Convert an array-like object into a true JavaScript array.

// jQuery
$.makeArray(arrayLike);

// Native
Array.prototype.slice.call(arrayLike);

// ES6-way
Array.from(arrayLike);

6.2 Contains

Check to see if a DOM element is a descendant of another DOM element.

// jQuery
$.contains(el, child);

// Native
el !== child && el.contains(child);

6.3 Globaleval

Execute some JavaScript code globally.

// jQuery
$.globaleval(code);

// Native
function Globaleval(code) {
  const script = document.createElement('script');
  script.text = code;

  document.head.appendChild(script).parentNode.removeChild(script);
}

// Use eval, but context of eval is current, context of $.Globaleval is global.
eval(code);

6.4 parse

parseHTML

Parses a string into an array of DOM nodes.

// jQuery
$.parseHTML(htmlString);

// Native
function parseHTML(string) {
  const context = document.implementation.createHTMLDocument();

  // Set the base href for the created document so any parsed elements with URLs
  // are based on the document's URL
  const base = context.createElement('base');
  base.href = document.location.href;
  context.head.appendChild(base);

  context.body.innerHTML = string;
  return context.body.children;
}

parseJSON

Takes a well-formed JSON string and returns the resulting JavaScript value.

// jQuery
$.parseJSON(str);

// Native
JSON.parse(str);

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Promises

A promise represents the eventual result of an asynchronous operation. jQuery has its own way to handle promises. Native JavaScript implements a thin and minimal API to handle promises according to the Promises/A+ specification.

7.1 done, fail, always

done is called when promise is resolved, fail is called when promise is rejected, always is called when promise is either resolved or rejected.

// jQuery
$promise.done(doneCallback).fail(failCallback).always(alwaysCallback)

// Native
promise.then(doneCallback, failCallback).then(alwaysCallback, alwaysCallback)

7.2 when

when is used to handle multiple promises. It will resolve when all promises are resolved, and reject if either one is rejected.

// jQuery
$.when($promise1, $promise2).done((promise1Result, promise2Result) => {
});

// Native
Promise.all([$promise1, $promise2]).then([promise1Result, promise2Result] => {});

7.3 Deferred

Deferred is a way to create promises.

// jQuery
function asyncFunc() {
  const defer = new $.Deferred();
  setTimeout(() => {
    if(true) {
      defer.resolve('some_value_computed_asynchronously');
    } else {
      defer.reject('failed');
    }
  }, 1000);

  return defer.promise();
}

// Native
function asyncFunc() {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      if (true) {
        resolve('some_value_computed_asynchronously');
      } else {
        reject('failed');
      }
    }, 1000);
  });
}

// Deferred way
function defer() {
  const deferred = {};
  const promise = new Promise((resolve, reject) => {
    deferred.resolve = resolve;
    deferred.reject = reject;
  });

  deferred.promise = () => {
    return promise;
  };

  return deferred;
}

function asyncFunc() {
  const defer = defer();
  setTimeout(() => {
    if(true) {
      defer.resolve('some_value_computed_asynchronously');
    } else {
      defer.reject('failed');
    }
  }, 1000);

  return defer.promise();
}

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Animation

8.1 Show & Hide

// jQuery
$el.show();
$el.hide();

// Native
// More detail about show method, please refer to https://github.com/oneuijs/oui-dom-utils/blob/master/src/index.js#L363
el.style.display = ''|'inline'|'inline-block'|'inline-table'|'block';
el.style.display = 'none';

8.2 Toggle

Display or hide the element.

// jQuery
$el.toggle();

// Native
if (el.ownerDocument.defaultView.getComputedStyle(el, null).display === 'none') {
  el.style.display = ''|'inline'|'inline-block'|'inline-table'|'block';
} else {
  el.style.display = 'none';
}

8.3 FadeIn & FadeOut

// jQuery
$el.fadeIn(3000);
$el.fadeOut(3000);

// Native
el.style.transition = 'opacity 3s';
// fadeIn
el.style.opacity = '1';
// fadeOut
el.style.opacity = '0';

8.4 FadeTo

Adjust the opacity of the element.

// jQuery
$el.fadeTo('slow',0.15);
// Native
el.style.transition = 'opacity 3s'; // assume 'slow' equals 3 seconds
el.style.opacity = '0.15';

8.5 FadeToggle

Display or hide the element by animating their opacity.

// jQuery
$el.fadeToggle();

// Native
el.style.transition = 'opacity 3s';
const { opacity } = el.ownerDocument.defaultView.getComputedStyle(el, null);
if (opacity === '1') {
  el.style.opacity = '0';
} else {
  el.style.opacity = '1';
}

8.6 SlideUp & SlideDown

// jQuery
$el.slideUp();
$el.slideDown();

// Native
const originHeight = '100px';
el.style.transition = 'height 3s';
// slideUp
el.style.height = '0px';
// slideDown
el.style.height = originHeight;

8.7 SlideToggle

Display or hide the element with a sliding motion.

// jQuery
$el.slideToggle();

// Native
const originHeight = '100px';
el.style.transition = 'height 3s';
const { height } = el.ownerDocument.defaultView.getComputedStyle(el, null);
if (parseInt(height, 10) === 0) {
  el.style.height = originHeight;
}
else {
 el.style.height = '0px';
}

8.8 Animate

Perform a custom animation of a set of CSS properties.

// jQuery
$el.animate({ params }, speed);

// Native
el.style.transition = 'all ' + speed;
Object.keys(params).forEach((key) =>
  el.style[key] = params[key];
)

Alternatives

You Might Not Need jQuery - Examples of how to do common event, element, ajax etc with plain javascript.
npm-dom and webmodules - Organizations you can find individual DOM modules on NPM