How to check the directory in ionic 4

I am using ionic 4, I want to check the file have inside my phone storage or not. If the file already inside the phone, I want to direct open the file no need download again my file, else I want to download the file. Can I know how to do it?

Here is my download file coding.

    .subscribe((res) => {
      const fileName =;

      this.file.writeFile(this.file.externalRootDirectory + 'Download/', fileName, res);

Anyone can help me? Thank you very much

You can try this approach

Good luck!

In addition

For native storage access like sd card erc you need cordova or capacitor

Stuff in your src/assets folder can be accessed with http

if possible can give me coding?