axios发送post请求，将数据以表单形式提交

axios({
    url: '/user',
    method: 'post',
    data: {
        firstName: 'Fred',
        lastName: 'Flintstone'
    },
    transformRequest: [function (data) {
        // Do whatever you want to transform the data
        let ret = ''
        for (let it in data) {
            ret += encodeURIComponent(it) + '=' + encodeURIComponent(data[it]) + '&'
        }
        return ret
    }],
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded'
    }
})