Javascript Express

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How to Learn Express.js

If you’ve worked with Node.js or any server-side programming in general, you’ve probably heard of Express.js. Express.js is widely used by companies like Fox Sports, IBM, and even Uber. We’re here to help you understand what it is, why it’s useful, and whether or not you should learn it.

Express.js is a framework designed to use Node.js specifically for running web servers. Eliminate the effort of having to code complex server-side integrations for Node.js.

Express.js much like a server in a box for JavaScript ; helps you easily use template solutions and organize your application routing with readable and well-organized code.

The only problem with Node.js is that while it is very useful for setting up servers, it was not designed specifically for this application. This is where Express.js comes in.

Express.js comes with a number of built-in features that work well in the server environment. These benefits include:

  • Faster server-side programming : Express.js takes a set of commonly used Node.js features and groups them into functions. These functions can be called anywhere in the program. This can save programmers hundreds of lines of code just by calling these functions instead of having to write them.
  • Routing: Node.js already has a routing mechanism, but it’s not very rudimentary. Express.js has a much more advanced and efficient routing mechanism that allows the web application to maintain the state of web pages only through their URLs.
  • Model : Express .js also has an engine model. This allows the server side to build the web page at its end and then send all of those values ‚Äã‚Äãto the front end for viewing. This enables dynamic content and reduces the load on the client side.

What is Express.js used for?

Express.js is a web framework that helps you organize your back end architecture. You will see that web developers use Express.js to implement a Model View Controller architecture. This allows a developer to write an easy to maintain backend code base.

Since Express.js runs on the backend, you can think of it as a technology that is the " brain behind a website ‚". Express.js can, for example, define how pages are routed on a website. Or a developer can use Express.js to handle authentication on a site.

Here are some of the use cases of Express.js:

  • Use of cookies on a website
  • Set up an authentication
  • Add a search bar to a site
  • Treat static files like images

Learn Express.js

Express.js is a useful technology to find out if you are interested in web development. Getting to know Express.js will not only help you write cleaner backend code, but will also help you advance your career prospects.

Below we will explain the Express learning process to you. .js.

How long does it take to learn Express.js?

It will take you a few days to a week to learn the basics of Express.js. This assumes that you have some experience working with JavaScript. If you want to learn more advanced topics, expect to spend at least a month or two learning.

Since Express.js is a background technology, to get started you will need a good understanding of how they work together in the back end and front end. you don’t have this training, expect to spend even more time learning the basics of Express.js.

How to Learn Express.js: Step by Step

There is no way you should learn Express.js. Every programmer is different and has different intentions for learning new technology. However, there are some common steps you can take to transition from beginner to expert effectively.

  1. Learn the basics of JavaScript . Express.js is a JavaScript framework. You will not be able to create an application using express.js as you will not create web applications with JavaScript and developed a deep understanding of syntax.
  2. Learn more about backend and front-end development . Spend some time learning about the front end and back end and their roles in a web application. This is crucial because Express.js is a backend tool. You will need to know the role of a backend framework to use Express.js.
  3. Practice your skills with Express.js . Open the Express.js documentation and start training with Express.js. Follow any tutorials you find interesting and spend your time mastering the basics of Express.js.
  4. Create a project . Building a plan will help you build your technical skills. Think about a web application you want to create and work to build it using Next.js.

Best Express.js Courses

Companies like IBM, FOX Sports, and Uber rely on Express.js. With that in mind, in addition to the size of the developer community, it’s no surprise that there are tons of Express.js resources available.

While this mean s that you have plenty of options, you might be wondering: are learning resources worth my time ? Below, we talk about some of the best Express.js online courses to help you narrow down your search.

ExpressJS Fundamentals teaches you how to create an Express.js server. You will learn about server-side applications, working with middleware, configuring model engines, and working with routes. These are all essential knowledge to have when working with Express.js.

Creation of a website with Node.js and Express.js

  • Editor: Lynda
  • Cost: Lynda subscription ($ 25 / month)
  • Public: Beginners

This course is for Node.js and Express beginners. js who want to build websites using these frameworks. You will learn how to build a basic Express.js application that uses multiple paths and templates. You will also learn how to handle POST requests and form data.

Learn Express by Codecademy

  • Provider: Codecademy
  • Cost: Pro subscription ( $ 16 / month)
  • Public: Beginners

Learn Express is an interactive beginners course Express.js. This course will teach you how to create a server using Express.js. You will learn about application paths, middelware and more.

Books Express .js online

Express in Action di Evan Mr. Hahn

Express in Action explains how to create a web application using Node.js and Express.js. In this book you will learn the basics of Node .js and Express.js and how to implement middleware and routing in your application.

Towards the end of this book, you will learn about data persistence, application security, and common best practices.

Pro Expr ess.js by Azat Marden

Professional Experience ress.js is a quick guide to using Express.js. The book begins with a simple hello to the world, and then broadly covers all of the API endpoints you will need to use. You will find exercises alongside the topics covered in this book that will help you build your skills.

Burn Web Application Development Using Express

This book is a comprehensive guide to building a web application using Express. js. You will cover topics such as using middleware and template engines, as well as the basics of RESTful API architecture. This book is great if you already have some Node.js skills and want to learn Express.js.

Express.js Resources Online

Getting started with Express.js

On the Express.js site, you will find a Getting Started Guide. This will walk you through installing Express.js and building your first web application. This tutorial is full of code snippets you can use to get started programming with Express.js.

Example GitHub repository Express.js < / a>

The Express.js team maintains a series of examples on how to use Express.js in the main GitHub repository project. You’ll find examples ranging from a simple hello world website to examples showing authentication and cookies in action.

Express.js and Node.js courses for beginners by freeCodeCamp

Taught by freeCodeCamp, this online video demonstrates the basics of using Express.js. You will learn about Node.js and its role in server-side development. Then you will continue to train with Express.js.

Express.js and Node.js

There is really no competition between Node.js and Express .js. In fact, the first thing to know about Express.js is that in a sense Express.js is Node.js. Express.js is a framework that runs in Node.js.

Node.js, if this term is new to you, is a JavaScript runtime. It allows you to run JavaScript code outside of your web browser. JavaScript is quite useful and you can do a lot of things with .

Being able to run JavaScript programs outside of a browser is especially useful when coding server-side backends for web programs in JavaScript. This is because most of the front-end web programming is already written in JavaScript, so allowing these programs to communicate with a backend that is JavaScript also improves functionality and speed.

Express.js lives on the stack

Express .js works best when implemented in a stack (a stack is all the code needed to run a web application, from front-end user interaction to the main processes resulting from that click). The Front-end and back-end development are usually separate, for good reason. However, this usually mean s that different developers are working on different parts of a puzzle that ultimately need to fit together.

Express.js works as efficiently as the second half of JavaScript front-end applications, allowing users to build an entire stack that adheres to a single language. It’s incredibly efficient because when it’s time for front-end developers to connect with back-end development work, there have been some integration issues. It goes without saying that things will (generally) work easier if everything is encoded in the same language.

The two most common JavaScript stacks that use Express.js are MEDIA stacks and NERD stacks. Remember, these are just acronyms, please don’t be mean to nerds! The MEAN stack mean s M ongoDB (the database), E xpress.js (the server), A ngular (the front-end framework) and N ode.js (the runtime environment).

The NERD stack is very similar. It stands for N ode.js (the runtime environment ; yes, they moved it to the foreground to make the acronym more fun), E xpress. js (the server), R eact (the front end) and D database (this can really be any database. This is because industry is moving away from sticking to a specific database ( and make the acronym more fun).

Currently the NERD stack is rapidly gaining popularity, making it the most relevant stack. But for the purposes of this article, both stacks use Express.js, which makes Express.js an interesting framework to learn. Bringing us to our next topic.

Why You Should Study Express.js

If you are planning to code for web development, you will likely learn JavaScript. Almost all modern websites use JavaScript. It’s such a widely used language that professional programmers make sure to keep it up to date and include it on their CVs. And many people start their programming journey with JavaScript.

In this regard, learning how to use Express.js effectively is not only useful if you plan to develop server-side backend software, but it is also a good way to fully understand how the web provides them. servers are running. Understanding the backend architecture of the server simplifies front-end development. So, whatever application you use JavaScript for, gaining a solid understanding of the extremely useful Express.js framework is a good idea.

Javascript Express __del__: Questions

How can I make a time delay in Python?

5 answers

I would like to know how to put a time delay in a Python script.

2973

Answer #1

import time
time.sleep(5)   # Delays for 5 seconds. You can also use a float value.

Here is another example where something is run approximately once a minute:

import time
while True:
    print("This prints once a minute.")
    time.sleep(60) # Delay for 1 minute (60 seconds).

2973

Answer #2

You can use the sleep() function in the time module. It can take a float argument for sub-second resolution.

from time import sleep
sleep(0.1) # Time in seconds

How to delete a file or folder in Python?

5 answers

How do I delete a file or folder in Python?

2639

Answer #1


Path objects from the Python 3.4+ pathlib module also expose these instance methods:

Javascript Express _files: Questions

How do I list all files of a directory?

5 answers

How can I list all files of a directory in Python and add them to a list?

3467

Answer #1

os.listdir() will get you everything that"s in a directory - files and directories.

If you want just files, you could either filter this down using os.path:

from os import listdir
from os.path import isfile, join
onlyfiles = [f for f in listdir(mypath) if isfile(join(mypath, f))]

or you could use os.walk() which will yield two lists for each directory it visits - splitting into files and dirs for you. If you only want the top directory you can break the first time it yields

from os import walk

f = []
for (dirpath, dirnames, filenames) in walk(mypath):
    f.extend(filenames)
    break

or, shorter:

from os import walk

filenames = next(walk(mypath), (None, None, []))[2]  # [] if no file

3467

Answer #2

I prefer using the glob module, as it does pattern matching and expansion.

import glob
print(glob.glob("/home/adam/*"))

It does pattern matching intuitively

import glob
# All files ending with .txt
print(glob.glob("/home/adam/*.txt")) 
# All files ending with .txt with depth of 2 folder
print(glob.glob("/home/adam/*/*.txt")) 

It will return a list with the queried files:

["/home/adam/file1.txt", "/home/adam/file2.txt", .... ]

3467

Answer #3

os.listdir() - list in the current directory

With listdir in os module you get the files and the folders in the current dir

 import os
 arr = os.listdir()
 print(arr)
 
 >>> ["$RECYCLE.BIN", "work.txt", "3ebooks.txt", "documents"]

Looking in a directory

arr = os.listdir("c:\files")

glob from glob

with glob you can specify a type of file to list like this

import glob

txtfiles = []
for file in glob.glob("*.txt"):
    txtfiles.append(file)

glob in a list comprehension

mylist = [f for f in glob.glob("*.txt")]

get the full path of only files in the current directory

import os
from os import listdir
from os.path import isfile, join

cwd = os.getcwd()
onlyfiles = [os.path.join(cwd, f) for f in os.listdir(cwd) if 
os.path.isfile(os.path.join(cwd, f))]
print(onlyfiles) 

["G:\getfilesname\getfilesname.py", "G:\getfilesname\example.txt"]

Getting the full path name with os.path.abspath

You get the full path in return

 import os
 files_path = [os.path.abspath(x) for x in os.listdir()]
 print(files_path)
 
 ["F:\documentiapplications.txt", "F:\documenticollections.txt"]

Walk: going through sub directories

os.walk returns the root, the directories list and the files list, that is why I unpacked them in r, d, f in the for loop; it, then, looks for other files and directories in the subfolders of the root and so on until there are no subfolders.

import os

# Getting the current work directory (cwd)
thisdir = os.getcwd()

# r=root, d=directories, f = files
for r, d, f in os.walk(thisdir):
    for file in f:
        if file.endswith(".docx"):
            print(os.path.join(r, file))

os.listdir(): get files in the current directory (Python 2)

In Python 2, if you want the list of the files in the current directory, you have to give the argument as "." or os.getcwd() in the os.listdir method.

 import os
 arr = os.listdir(".")
 print(arr)
 
 >>> ["$RECYCLE.BIN", "work.txt", "3ebooks.txt", "documents"]

To go up in the directory tree

# Method 1
x = os.listdir("..")

# Method 2
x= os.listdir("/")

Get files: os.listdir() in a particular directory (Python 2 and 3)

 import os
 arr = os.listdir("F:\python")
 print(arr)
 
 >>> ["$RECYCLE.BIN", "work.txt", "3ebooks.txt", "documents"]

Get files of a particular subdirectory with os.listdir()

import os

x = os.listdir("./content")

os.walk(".") - current directory

 import os
 arr = next(os.walk("."))[2]
 print(arr)
 
 >>> ["5bs_Turismo1.pdf", "5bs_Turismo1.pptx", "esperienza.txt"]

next(os.walk(".")) and os.path.join("dir", "file")

 import os
 arr = []
 for d,r,f in next(os.walk("F:\_python")):
     for file in f:
         arr.append(os.path.join(r,file))

 for f in arr:
     print(files)

>>> F:\_python\dict_class.py
>>> F:\_python\programmi.txt

next(os.walk("F:\") - get the full path - list comprehension

 [os.path.join(r,file) for r,d,f in next(os.walk("F:\_python")) for file in f]
 
 >>> ["F:\_python\dict_class.py", "F:\_python\programmi.txt"]

os.walk - get full path - all files in sub dirs**

x = [os.path.join(r,file) for r,d,f in os.walk("F:\_python") for file in f]
print(x)

>>> ["F:\_python\dict.py", "F:\_python\progr.txt", "F:\_python\readl.py"]

os.listdir() - get only txt files

 arr_txt = [x for x in os.listdir() if x.endswith(".txt")]
 print(arr_txt)
 
 >>> ["work.txt", "3ebooks.txt"]

Using glob to get the full path of the files

If I should need the absolute path of the files:

from path import path
from glob import glob
x = [path(f).abspath() for f in glob("F:\*.txt")]
for f in x:
    print(f)

>>> F:acquistionline.txt
>>> F:acquisti_2018.txt
>>> F:ootstrap_jquery_ecc.txt

Using os.path.isfile to avoid directories in the list

import os.path
listOfFiles = [f for f in os.listdir() if os.path.isfile(f)]
print(listOfFiles)

>>> ["a simple game.py", "data.txt", "decorator.py"]

Using pathlib from Python 3.4

import pathlib

flist = []
for p in pathlib.Path(".").iterdir():
    if p.is_file():
        print(p)
        flist.append(p)

 >>> error.PNG
 >>> exemaker.bat
 >>> guiprova.mp3
 >>> setup.py
 >>> speak_gui2.py
 >>> thumb.PNG

With list comprehension:

flist = [p for p in pathlib.Path(".").iterdir() if p.is_file()]

Alternatively, use pathlib.Path() instead of pathlib.Path(".")

Use glob method in pathlib.Path()

import pathlib

py = pathlib.Path().glob("*.py")
for file in py:
    print(file)

>>> stack_overflow_list.py
>>> stack_overflow_list_tkinter.py

Get all and only files with os.walk

import os
x = [i[2] for i in os.walk(".")]
y=[]
for t in x:
    for f in t:
        y.append(f)
print(y)

>>> ["append_to_list.py", "data.txt", "data1.txt", "data2.txt", "data_180617", "os_walk.py", "READ2.py", "read_data.py", "somma_defaltdic.py", "substitute_words.py", "sum_data.py", "data.txt", "data1.txt", "data_180617"]

Get only files with next and walk in a directory

 import os
 x = next(os.walk("F://python"))[2]
 print(x)
 
 >>> ["calculator.bat","calculator.py"]

Get only directories with next and walk in a directory

 import os
 next(os.walk("F://python"))[1] # for the current dir use (".")
 
 >>> ["python3","others"]

Get all the subdir names with walk

for r,d,f in os.walk("F:\_python"):
    for dirs in d:
        print(dirs)

>>> .vscode
>>> pyexcel
>>> pyschool.py
>>> subtitles
>>> _metaprogramming
>>> .ipynb_checkpoints

os.scandir() from Python 3.5 and greater

import os
x = [f.name for f in os.scandir() if f.is_file()]
print(x)

>>> ["calculator.bat","calculator.py"]

# Another example with scandir (a little variation from docs.python.org)
# This one is more efficient than os.listdir.
# In this case, it shows the files only in the current directory
# where the script is executed.

import os
with os.scandir() as i:
    for entry in i:
        if entry.is_file():
            print(entry.name)

>>> ebookmaker.py
>>> error.PNG
>>> exemaker.bat
>>> guiprova.mp3
>>> setup.py
>>> speakgui4.py
>>> speak_gui2.py
>>> speak_gui3.py
>>> thumb.PNG

Examples:

Ex. 1: How many files are there in the subdirectories?

In this example, we look for the number of files that are included in all the directory and its subdirectories.

import os

def count(dir, counter=0):
    "returns number of files in dir and subdirs"
    for pack in os.walk(dir):
        for f in pack[2]:
            counter += 1
    return dir + " : " + str(counter) + "files"

print(count("F:\python"))

>>> "F:\python" : 12057 files"

Ex.2: How to copy all files from a directory to another?

A script to make order in your computer finding all files of a type (default: pptx) and copying them in a new folder.

import os
import shutil
from path import path

destination = "F:\file_copied"
# os.makedirs(destination)

def copyfile(dir, filetype="pptx", counter=0):
    "Searches for pptx (or other - pptx is the default) files and copies them"
    for pack in os.walk(dir):
        for f in pack[2]:
            if f.endswith(filetype):
                fullpath = pack[0] + "\" + f
                print(fullpath)
                shutil.copy(fullpath, destination)
                counter += 1
    if counter > 0:
        print("-" * 30)
        print("	==> Found in: `" + dir + "` : " + str(counter) + " files
")

for dir in os.listdir():
    "searches for folders that starts with `_`"
    if dir[0] == "_":
        # copyfile(dir, filetype="pdf")
        copyfile(dir, filetype="txt")


>>> _compiti18Compito Contabilità 1conti.txt
>>> _compiti18Compito Contabilità 1modula4.txt
>>> _compiti18Compito Contabilità 1moduloa4.txt
>>> ------------------------
>>> ==> Found in: `_compiti18` : 3 files

Ex. 3: How to get all the files in a txt file

In case you want to create a txt file with all the file names:

import os
mylist = ""
with open("filelist.txt", "w", encoding="utf-8") as file:
    for eachfile in os.listdir():
        mylist += eachfile + "
"
    file.write(mylist)

Example: txt with all the files of an hard drive

"""
We are going to save a txt file with all the files in your directory.
We will use the function walk()
"""

import os

# see all the methods of os
# print(*dir(os), sep=", ")
listafile = []
percorso = []
with open("lista_file.txt", "w", encoding="utf-8") as testo:
    for root, dirs, files in os.walk("D:\"):
        for file in files:
            listafile.append(file)
            percorso.append(root + "\" + file)
            testo.write(file + "
")
listafile.sort()
print("N. of files", len(listafile))
with open("lista_file_ordinata.txt", "w", encoding="utf-8") as testo_ordinato:
    for file in listafile:
        testo_ordinato.write(file + "
")

with open("percorso.txt", "w", encoding="utf-8") as file_percorso:
    for file in percorso:
        file_percorso.write(file + "
")

os.system("lista_file.txt")
os.system("lista_file_ordinata.txt")
os.system("percorso.txt")

All the file of C: in one text file

This is a shorter version of the previous code. Change the folder where to start finding the files if you need to start from another position. This code generate a 50 mb on text file on my computer with something less then 500.000 lines with files with the complete path.

import os

with open("file.txt", "w", encoding="utf-8") as filewrite:
    for r, d, f in os.walk("C:\"):
        for file in f:
            filewrite.write(f"{r + file}
")

How to write a file with all paths in a folder of a type

With this function you can create a txt file that will have the name of a type of file that you look for (ex. pngfile.txt) with all the full path of all the files of that type. It can be useful sometimes, I think.

import os

def searchfiles(extension=".ttf", folder="H:\"):
    "Create a txt file with all the file of a type"
    with open(extension[1:] + "file.txt", "w", encoding="utf-8") as filewrite:
        for r, d, f in os.walk(folder):
            for file in f:
                if file.endswith(extension):
                    filewrite.write(f"{r + file}
")

# looking for png file (fonts) in the hard disk H:
searchfiles(".png", "H:\")

>>> H:4bs_18Dolphins5.png
>>> H:4bs_18Dolphins6.png
>>> H:4bs_18Dolphins7.png
>>> H:5_18marketing htmlassetsimageslogo2.png
>>> H:7z001.png
>>> H:7z002.png

(New) Find all files and open them with tkinter GUI

I just wanted to add in this 2019 a little app to search for all files in a dir and be able to open them by doubleclicking on the name of the file in the list. enter image description here

import tkinter as tk
import os

def searchfiles(extension=".txt", folder="H:\"):
    "insert all files in the listbox"
    for r, d, f in os.walk(folder):
        for file in f:
            if file.endswith(extension):
                lb.insert(0, r + "\" + file)

def open_file():
    os.startfile(lb.get(lb.curselection()[0]))

root = tk.Tk()
root.geometry("400x400")
bt = tk.Button(root, text="Search", command=lambda:searchfiles(".png", "H:\"))
bt.pack()
lb = tk.Listbox(root)
lb.pack(fill="both", expand=1)
lb.bind("<Double-Button>", lambda x: open_file())
root.mainloop()

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