Q:

How to get a list of all files in Cloud Storage in a Firebase app?

I'm working on uploading images, everything works great, but I have 100 pictures and I would like to show all of them in my View, as I get the complete list of the images in a folder, I can not find any API for this work. 

A:

Since Firebase SDKs for JavaScript release 6.1, iOS release 6.4, and Android release version 18.1 all have a method to list files. 
The documentation is a bit sparse so far, so I recommend checking out Rosário's answer for details.

Previous answer, since this approach can still be useful at times:
There currently is no API call in the Firebase SDK to list all files in a Cloud Storage folder from within an app. If you need such functionality, you should store the metadata of the files (such as the download URLs) in a place where you can list them. The Firebase Realtime Database and Cloud Firestore are perfect for this and allows you to also easily share the URLs with others.
You can find a good (but somewhat involved) sample of this in our FriendlyPix sample app. The relevant code for the web version is here, but there are also versions for iOS and Android.

A:

As of May 2019, version 6.1.0 of the Firebase SDK for Cloud Storage now supports listing all objects from a bucket. You simply need to call listAll() in a Reference:
    // Since you mentioned your images are in a folder,
    // we'll create a Reference to that folder:
    var storageRef = firebase.storage().ref("your_folder");

    // Now we get the references of these images
    storageRef.listAll().then(function(result) {
      result.items.forEach(function(imageRef) {
        // And finally display them
        displayImage(imageRef);
      });
    }).catch(function(error) {
      // Handle any errors
    });

    function displayImage(imageRef) {
      imageRef.getDownloadURL().then(function(url) {
        // TODO: Display the image on the UI
      }).catch(function(error) {
        // Handle any errors
      });
    }

Please note that in order to use this function, you must opt-in to version 2 of Security Rules, which can be done by making rules_version = '2'; the first line of your security rules:
    rules_version = '2';
    service firebase.storage {
      match /b/{bucket}/o {
        match /{allPaths=**} {

I'd recommend checking the docs for further reference.
Also, according to setup, on Step 5, this script is not allowed for Node.js since require("firebase/app"); won't return firebase.storage() as a function. This is only achieved using import * as firebase from 'firebase/app';.

A:

Since Mar 2017: With the addition of Firebase Cloud Functions, and Firebase's deeper integration with Google Cloud, this is now possible. 
With Cloud Functions you can use the Google Cloud Node package to do epic operations on Cloud Storage. Below is an example that gets all the file URLs into an array from Cloud Storage. This function will be triggered every time something's saved to google cloud storage. 
Note 1: This is a rather computationally expensive operation, as it has to cycle through all files in a bucket / folder. 
Note 2: I wrote this just as an example, without paying much detail into promises etc. Just to give an idea.
const functions = require('firebase-functions');
const gcs = require('@google-cloud/storage')();

// let's trigger this function with a file upload to google cloud storage

exports.fileUploaded = functions.storage.object().onChange(event => {

  const object = event.data; // the object that was just uploaded
  const bucket = gcs.bucket(object.bucket);
  const signedUrlConfig = { action: 'read', expires: '03-17-2025' }; // this is a signed url configuration object

  var fileURLs = []; // array to hold all file urls 

  // this is just for the sake of this example. Ideally you should get the path from the object that is uploaded :)
  const folderPath = "a/path/you/want/its/folder/size/calculated";

  bucket.getFiles({ prefix: folderPath }, function(err, files) {
    // files = array of file objects
    // not the contents of these files, we're not downloading the files. 

    files.forEach(function(file) {
      file.getSignedUrl(signedUrlConfig, function(err, fileURL) {
        console.log(fileURL);
        fileURLs.push(fileURL);
      });
    });

  });

});

I hope this will give you the general idea. For better cloud functions examples, check out Google's Github repo full of Cloud Functions samples for Firebase. Also check out their Google Cloud Node API Documentation

