CODE EXAMPLE FOR JAVASCRIPT

js regex

// get "bucket1337" from https://bucket1337.appspot.com.storage.googleapis.com/staging/blender_input/162480.glb"

//define string
let string = "https://bucket1337.appspot.com.storage.googleapis.com/staging/blender_input/162480.glb"

//define regexp
let bucketRegex = new RegExp(`(?<=https://).*(?=.app)`, 'gm')

// execute regexp
let result = string.match(bucketRegex)[0]