Uploading multiple files to a Absinthe backend.

I am trying to upload a file list as list_of(upload) to my Absinthe backend. Here is my JS code for submitting the request.

    const query = "mutation { uploadImages(files: \"image_files\")}"
    let formData = new FormData();
    formData.append('query', query);
    for( var i = 0; i < this.files.length; i++ ){
      let file = this.files[i];
      formData.append('image_files[' + i + ']', file);

I am not getting the files as a list of uploads. Not sure, where I am doing wrong. Any help is much appreciated. I am able to upload a single file in the way.