if (workLength > 0) {
var link = document.querySelector('link[rel*="icon"]') ||document.createElement('link')
link.type = 'image/x-icon'
link.rel = 'shortcut icon'
link.href = 'http://www.stackoverflow.com/favicon.ico'
document.getElementsByTagName('head')[0].appendChild(link)
}
即可实现切换,那些看着数字变化的其实都是图片,不要怕怕哦