Empty post post - problem with file reader

Hello, I'm developing in an application using angular 2. I use dropzone.js to upload files. The problem is this: When I load the files directly from dropzone to an array of files, as in the code below:

this.showUploadFileNotAllowed = false;
    if (this.myDropzone.files.length !== 0) {
        for (var i = 0; i < this.myDropzone.files.length; i++) {
            if (this.myDropzone.files[i].size > 5242880) {
                this.showUploadFileNotAllowed = true;
                this.showUploadMaxSizeExceed = true;
            }
        }
        for (var i = 0; i < this.myDropzone.files.length; i++) {
              this.attachmentsArray.push({
                  filename: this.myDropzone.files[i].name,
                  content: this.myDropzone.files[i].dataURL.split('base64,')[1],
                  encoding: 'base64', 
             })

        }
    }

works perfectly (for image files). How can you see the response of the post:

However,sinceIneedtosendotherfileformats,Idecidedtousethefilereaderasinthefollowingmethods:

publicgetBase64(file,i){varreader=newFileReader();reader.readAsDataURL(file);reader.onload=(el=>{this.loadAttachments(file.name,reader.result.split('base64,')[1]);});reader.onerror=function(error){console.log('Error:',error);};}publicloadAttachments(name,content){console.log(content);this.attachmentsArray.push({filename:name,content:content,encoding:'base64',})}

SoinsteadofdoingthatdirectdropzonepushImakethegetBase64methodcall.Butthiswaythearray"attachments" in the post goes empty. Could anyone give a light of what could be the problem?