javascript - 在同一组件内调用函数表示 this.checkUpdate 不是函数

Question

我有以下上传功能，可将文件上传到 s3

   _.each(files, file => {
      let uuid = this.appMsgService.getGUID();
      let bucket = new AWS.S3({ params: { Bucket: 'myBucket' } });
      let params = { Key: `\source/${uuid}.pdf`, Body: file };
      this.fileNames[file.name] = `${uuid}.pdf`;
      this.fileName = `${uuid}`;
      bucket.upload(params, function (error: any, res: any) {
        uploadCount += 1;
        console.log('error', error);
        console.log('response', res);
        if (uploadCount === files.length) {
          this.interval = setInterval(() => {
            console.log(JSON.stringify(this.fileNames));
            this.checkUpdate(this.fileNames);
          }, 3000);
        }
      });

    });

我在同一组件内还有另一个函数，使用计时器调用该函数并检查更新

checkUpdate(filenames: any) {
}

我已在上传的回调中添加了方法调用，但它给出了一个错误，指出_this.checkUpdate is not a function

Answer 1

改变

bucket.upload(params, function (error:any, res:any) {

至

bucket.upload(params, (error: any, res: any)=> {

您的 this 并未引用您的组件。

旧的js方式:

var self = this; //<-- use self to refer to the component in the lexical scope
bucket.upload(params, function (error: any, res: any) {
    uploadCount += 1;
    console.log('error', error);
    console.log('response', res);
    if (uploadCount === files.length) {
    self.interval = setInterval(() => {
        console.log(JSON.stringify(self.fileNames));
            self.checkUpdate(self.fileNames);
        }, 3000);
    }
});