Question

我对node.js和javascript一般都比较新。特别是，我对promises和async / await感到困惑。我试图从远程URL异步请求图像并将它们转换为base64。有人可以解释下面我的代码有什么问题吗？

    function loadAsync(image){
        return new Promise(function(resolve,reject){
            request({url: image, encoding: null}, function (err, res, body) {
                if (!err && res.statusCode == 200) {
                    let base64prefix = 'data:' + res.headers['content-type'] + ';base64,'
                    let image = body.toString('base64');
                    let complete = base64prefix + image;
                    resolve(complete)
                } else {
                    return reject(err);
                }
            });     
        });
    }

    async function getImagesAsBase64(images){
        let promises = [];
        images.forEach(image =>{
            promises.push(loadAsync(image).then(results =>{
                return results;
            }));
        });
        const imagesAsBase64 = await Promise.all(promises);
        return imagesAsBase64;
    }

   //Following returns Promise{<pending>} when given an array of images
   console.log(getImagesAsBase64(images));

Answer 1

愚蠢的我，我需要await结果

let imagesAsBase64 = await getImagesAsBase64(images);
console.log(imagesAsBase64);

不正确理解async / await / promise如何工作

1 个答案: