monaca-stock-management-firebase-upload-picture.js

// Uploading picture
function uploadImageToFirebaseStorage(elementName, fileName, img, edit) {
  // // Create a reference for the storage, the folder and the filename
  const storageRef = firebase.storage().ref('products/' + fileName);
  // Upload the file and metadata
  const uploadTask = storageRef.putString(img, 'base64');

  // Register three observers:
   // 1. 'state_changed' observer, called any time the state changes
   // 2. Error observer, called on failure
   // 3. Completion observer, called on successful completion
  uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED,
    function (snapshot) {
      // Observe state change events such as progress, pause, and resume
      // Get task progress, including the number of bytes uploaded and the total number of bytes to be uploaded
      const progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
      elementName.innerHTML = 'Upload is ' + Math.trunc(progress) + '% done';

      if (progress == 100) {
        if (edit) 
          app.dialog.alert('Saved product details.', '');
        else {
          app.dialog.alert("Product added to the products list.", "");
          app.methods.emptyNewProductForm();
          document.getElementById("imageFile").src = "assets/pictures/camera.png";
          elementName.innerHTML = "";
        }
      }

      switch (snapshot.state) {
        case firebase.storage.TaskState.PAUSED:
          console.log('Upload is paused'); // or 'paused'
          break;
        case firebase.storage.TaskState.RUNNING:
          console.log('Upload is running'); // or 'running'
          break;
      }
    },
    function (error) {
    // Handle unsuccessful uploads
      switch (error.code) {
        case 'storage/unauthorized':
          break;
        case 'storage/canceled':
          break;
        case 'storage/unknown':
          break;
        case 'storage/invalid-format':
          break;
      }
    });
}