success返回值怎么给外部变量赋值

function Info(uid) {

var that = this;

var head;

wx.request({

url: ‘’,

data: {

},

header: {

‘content-type’: ‘application/json’

},

success(res) {

that.head = res.data.head;

console.log(that.head);

}

})

console.log(that.head)

return that.head;

}

module.exports.Info = Info;