问题
I've got this working on mobile devices, but because of the 32kb gzip-ed of jQuery I wonder if it's possible to create this code
$(document).ready(function() {
$('body').addClass('js');
var $menu = $('#menu'),
$menulink = $('.menu-link'),
$wrap = $('#wrap');
$menulink.click(function() {
$menulink.toggleClass('active');
$wrap.toggleClass('active');
return false;
});
});
can be written in no library dependany vanilla JavaScript.
Can it be done? Where would I start?
回答1:
JQuery uses javascript/DOMscripting to create its framework. Everything JQuery does, can be done in basic scripting. For example $('body').addClass('js')
can be written as:
document.querySelector('body').className += ' js';
And $menulink.toggleClass('active');
as something like
var current = $menulink.className.split(/\s+/)
,toggleClass = 'active'
,exist = ~current.indexOf(toggleClass)
;
current.splice(exist ? current.indexOf(toggleClass) : 0,
exist ? 1 : 0,
exist ? null : toggleClass);
$menulink.className = current.join(' ').replace(/^\s+|\s+$/,'');
That's why JQuery wrapped this kind of code.
This jsfiddle contains a working example using javascript without a framework. Besides that it demonstrates how to program your own element wrapper.
Where to start? You'll have to dive into javascript I suppose. Or check this SO-question
回答2:
For modern browsers only.®
document.addEventListener('DOMContentLoaded', function() {
document.body.classList.add('js');
var wrap = document.getElementById('wrap');
var menuLinks = Array.prototype.slice.call(document.getElementsByClassName('menu-link'));
var toggleActive = function(element) {
element.classList.toggle('active');
};
menuLinks.forEach(function(menuLink) {
menuLink.addEventListener('click', function(e) {
menuLinks.forEach(toggleActive);
toggleActive(wrap);
}, false);
});
}, false);
回答3:
var toggleClass = function (el, className) {
if(el) {
if(el.className.indexOf(className)) {
el.className = el.className.replace(className, '');
}
else {
el.className += ' ' + className;
}
}
};
document.addEventListener('DOMContentLoaded', function () {
document.body.className += ' js';
var $menu = document.querySelector('#menu'),
$menulink = document.querySelectorAll('.menu-link'),
$wrap = document.querySelector('#wrap');
$menulink.addEventListener('click', function (e) {
toggleClass($menulink, 'active');
toggleClass($wrap, 'active');
e.preventDefault();
});
});
回答4:
There's always classList (workaround for incompatible browsers included).
回答5:
Absolutely. Since jQuery is a subset of JavaScript (written entirely in JavaScript) any function you like can be duplicated. It's a matter of how much effort you want to put into it. Below is how I would duplicate the limited subset of jQuery in your post and it's reasonably cross-browser compatible (if a wee bit long...).
var Vanilla;
if (!Vanilla) {
Vanilla = {};
}
//execute this now to have access to it immediately.
(function () {
'use strict';
Vanilla.addHandler = function (elem, event, handler) {
if (elem.addEventListener) {
elem.addEventListener(event, handler, false);
} else if (elem.attachEvent) {
elem.attachEvent('on' + event, handler);
}
};
Vanilla.hasClass = function (elem, cssClass) {
var classExists = false;
//
if (elem && typeof elem.className === 'string' && (/\S+/g).test(cssClass)) {
classExists = elem.className.indexOf(cssClass) > -1;
}
//
return classExists;
};
Vanilla.addClass = function (elem, cssClass) {
if (elem && typeof elem.className === 'string' && (/\S+/g).test(cssClass)) {
//put spaces on either side of the new class to ensure boundaries are always available
elem.className += ' ' + cssClass + ' ';
}
};
Vanilla.removeClass = function (elem, cssClass) {
if (elem && typeof elem.className === 'string'&& (/\S+/g).test(cssClass)) {
//replace the string with regex
cssClass = new RegExp('\\b' + cssClass + '\\b', 'g');
elem.className = elem.className.replace(cssClass, '').replace(/^\s+/g, '').replace(/\s+$/g, ''); //trim className
}
};
Vanilla.toggleClass = function (elem, cssClass) {
if (Vanilla.hasClass(elem, cssClass)) {
Vanilla.removeClass(elem, cssClass);
} else {
Vanilla.addClass(elem, cssClass);
}
};
Vanilla.getElementsByClassName = function (cssClass) {
var nodeList = [],
classList = [],
allNodes = null,
i = 0,
j = 0;
if (document.getElementsByClassName1) {
//native method exists in browser.
nodeList = document.getElementsByClassName(cssClass);
} else {
//need a custom function
classList = cssClass.split(' ');
allNodes = document.getElementsByTagName('*');
for (i = 0; i < allNodes.length; i += 1) {
for (j = 0; j < classList.length; j += 1) {
if (Vanilla.hasClass(allNodes[i], classList[j])) {
nodeList.push(allNodes[i]);
}
}
}
}
return nodeList;
};
}());
//Now we have a proper window onload
Vanilla.addHandler(window, 'load', function () {
'use strict';
var body = document.body,
menu = document.getElementById('menu'),
menulink = [],
wrap = document.getElementById('wrap'),
i = 0,
menulinkClickHandler = function (e) {
var i = 0;
for (i = 0; i < menulink.length; i += 1) {
Vanilla.toggleClass(menulink[i], 'active');
}
Vanilla.toggleClass(wrap, 'active');
return false;
};
Vanilla.addClass(body, 'js');
menulink = Vanilla.getElementsByClassName('menu-link');
for (i = 0; i < menulink.length; i += 1) {
Vanilla.addHandler(menulink[i], 'click', menulinkClickHandler);
}
});
来源:https://stackoverflow.com/questions/12874006/can-this-jquery-be-done-in-vanilla-js