JavaScript根据CSS的Media Queries来判断浏览设备的方法_html/css_WEB-ITnose
CSS 部分
首先随便新建一个用来做判断的类,然后通过 Media Queries 来对这个类的 z-index 属性赋予不同的值。这个类仅作为 JavaScript 读取使用,所以需要将其移出屏幕窗口,让浏览者不可见以免引起意外情况。
作为演示,下面代码设置了四种设备状态:桌面普通版、小屏幕桌面版、平板电脑版和手机版。
/* default state */.state-indicator { position: absolute; top: -999em; left: -999em; z-index: 1;} /* small desktop */@media all and (max-width: 1200px) { .state-indicator { z-index: 2; }} /* tablet */@media all and (max-width: 1024px) { .state-indicator { z-index: 3; }} /* mobile phone */@media all and (max-width: 768px) { .state-indicator { z-index: 4; }}
JavaScript 判断
CSS 已经就位了,那么就需要用 JavaScript 来生成了一个临时的 DOM 对象,然后为它设置对应的类,然后再读取这个对象的 z-index 值。原生的写法如下:
// Create the state-indicator elementvar indicator = document.createElement('div');indicator.className = 'state-indicator';document.body.appendChild(indicator); // Create a method which returns device statefunction getDeviceState() { return parseInt(window.getComputedStyle(indicator).getPropertyValue('z-index'), 10);}getDeviceState() 函数返回的就是 z-index 的值,为了增强一下可读性,可以用 switch 函数来规范输出一下: function getDeviceState() { switch(parseInt(window.getComputedStyle(indicator).getPropertyValue('z-index'), 10)) { case 2: return 'small-desktop'; break; case 3: return 'tablet'; break; case 4: return 'phone'; break; default: return 'desktop'; break; }}
这样,就可以用一下代码来判断设备状态,然后执行相应的 JavaScript 代码:
if(getDeviceState() == 'tablet') { // 平板电脑下执行的 JavaScript 代码}
这里如果你使用的是 jQuery,直接使用下面代码就可以了:
$(function(){ $('body').append('<div class="state-indicator"></div>'); function getDeviceState() { switch(parseInt($('.state-indicator').css('z-index'),10)) { case 2: return 'small-desktop'; break; case 3: return 'tablet'; break; case 4: return 'phone'; break; default: return 'desktop'; break; } } console.log(getDeviceState()); $('.state-indicator').remove();});

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics



HTML is suitable for beginners because it is simple and easy to learn and can quickly see results. 1) The learning curve of HTML is smooth and easy to get started. 2) Just master the basic tags to start creating web pages. 3) High flexibility and can be used in combination with CSS and JavaScript. 4) Rich learning resources and modern tools support the learning process.

The article discusses the HTML <progress> element, its purpose, styling, and differences from the <meter> element. The main focus is on using <progress> for task completion and <meter> for stati

HTML defines the web structure, CSS is responsible for style and layout, and JavaScript gives dynamic interaction. The three perform their duties in web development and jointly build a colorful website.

The article discusses the HTML <datalist> element, which enhances forms by providing autocomplete suggestions, improving user experience and reducing errors.Character count: 159

The article discusses the HTML <meter> element, used for displaying scalar or fractional values within a range, and its common applications in web development. It differentiates <meter> from <progress> and ex

AnexampleofastartingtaginHTMLis,whichbeginsaparagraph.StartingtagsareessentialinHTMLastheyinitiateelements,definetheirtypes,andarecrucialforstructuringwebpagesandconstructingtheDOM.

WebdevelopmentreliesonHTML,CSS,andJavaScript:1)HTMLstructurescontent,2)CSSstylesit,and3)JavaScriptaddsinteractivity,formingthebasisofmodernwebexperiences.

GiteePages static website deployment failed: 404 error troubleshooting and resolution when using Gitee...
