判断当前网络状态
window.addEventListener('online', function (e) {
console.log('网络链接')
})
window.addEventListener('offline', function () {
console.log('网络断开')
})
window.addEventListener('online', function (e) {
console.log('网络链接')
})
window.addEventListener('offline', function () {
console.log('网络断开')
})