node.js - 如何获取requet里面异步回调的值？代码里面的ret

function reqst(key,callback){
    var res="";
    request({
        method:"GET",
        url:encodeURI(`http://news.baidu.com/ns?cl=2&rn=20&tn=news&word=${key}`)
    },(err,res,body)=>{
        if(!err&&res.statusCode==200){
            let ret=[];
            let $ = cheerio.load(body)
            let datas = Array.from($(".result")).splice(0,5);
            for (var i = datas.length - 1; i >= 0; i--) {
                let data = {
                    title:$(datas[i]).find('.c-title').text(),    
                    author:$(datas[i]).find('.c-author').text(),
                    summary:$(datas[i]).find('.c-summary').text()
                }
                ret.unshift(data)
            }
        }        
    })
    return true;
}