使用new AbortController

 let getCodeBtn = document.querySelector('#getCode')
    let controller = null
    getCodeBtn.addEventListener('click',() => {
        console.log('发起请求')
        if(controller) {
            controller.abort()
            controller = null
        }
        controller = new AbortController()
        axios({
            method:"GET",
            url:'http://localhost:9066/longPollication',
            signal:controller.signal
        }).then(val => {
            let {data:res} = val
            console.log('res',res)
        }).catch(err => {
            console.log(err)
        })
    })

使用CancelToken 准备废弃

const cancelToken = axios.CancelToken
    let source = null
    document.querySelector('#cancelToken').addEventListener('click',() => {
        if(source) {
            source.cancel()
            source = null
        }
        source = cancelToken.source()
        axios({
            method:"GET",
            url:'http://localhost:9066/longPollication',
            cancelToken:source.token
        }).then(val => {
            let {data:res} = val
            console.log('res',res)
        }).catch(err => {
            console.log(err)
        })
    })