DEV Community: Murtaja Ziad

How to calculate the number of days between 2 dates in Python?

Murtaja Ziad — Fri, 05 Feb 2021 11:00:00 +0000

In this article, you will learn how to calculate the number of days between 2 dates in Python.

At the beginning, import date from datetime..

from datetime import date

Then, define the first and second date

first_date = date(2021, 1, 31)
second_date = date(2021, 2, 28)

Then, calculate second_date - first_date

difference = second_date - first_date

At the end, print difference.days

print(difference.days) # 28

How to flatten an array in JavaScript?

Murtaja Ziad — Fri, 22 Jan 2021 11:00:00 +0000

In this article, you will learn how to flat an array in JavaScript.

That’s the array of arrays that we have:

let arrays = [[1, 2], [3, 4], [5]];

You can flat it easily using .flat() method and assigning it to a new variable:

let flattenedArray = arrays.flat();

If you want to see the flattened array, just log it to the console:

console.log(flattenedArray); // [1, 2, 3, 4, 5]

and yeah, it’s working :D

Divide a list in half using Python.

Murtaja Ziad — Fri, 15 Jan 2021 11:00:00 +0000

You can divide a list into two pieces using the following code..

def split_list(a_list):
    half = len(a_list) // 2
    return a_list[:half], a_list[half:]

first_piece, second_piece = split_list([1,2,3,4])
print(first_piece, second_piece)

As you see, this function will split a list into two lists the first one in the example will be [1, 2] and the second one will be [3, 4].

How to remove the last character of a string in Python?

Murtaja Ziad — Fri, 08 Jan 2021 11:00:00 +0000

You can remove the last character of a string using Python easily by removing the last index of the string.

string = "abcdef"
print(string[:-1]) # abcde

[:-1] means get the string starting from beginning to the end excluding the last character. Also, you can use it with any index using this syntax: string[start:stop].

How to remove the first character of a string in Python?

Murtaja Ziad — Fri, 01 Jan 2021 11:00:00 +0000

You can remove the first character of a string using Python easily by removing the first index of the string.

string = "abcdef"
print(string[1:]) # bcdef

[1:] means get the string starting from index 1 to the end. Also, you can use it with any index using this syntax: string[start:stop].

6 tips for being a better programmer.

Murtaja Ziad — Fri, 25 Dec 2020 11:00:00 +0000

In this article, I will show you 6 tips for being a better programmer.

1. Name variables appropriately.

The variable name should define its value, so you shouldn’t name a variable something like x, y, or z.

2. Read the documentation.

Documentation is the source of everything, including educational videos. So, reading them makes you an expert.

3. Split your code.

Instead of writing everything in one large function, split your code into multiple smaller functions.

4. Add comments to your codes.

Nothing is worse than not understanding the code that you wrote a month earlier, right?

5. Build a portfolio.

Make a website and put your work inside it, so people can see your programming and designing uncomplicated!

6. Learn to read others’ code.

When you join a new company, you’re more likely to continue an existing project, so you should be able to read others’ code and improve it.

Check if a value exists in an array using Javascript.

Murtaja Ziad — Fri, 18 Dec 2020 11:00:00 +0000

In this article, I will show you the 2 ways for checking if a value exists in an array.

1. Using includes()

This method returns true if the array includes the value, else it returns false.

let array = ["a", "b", "c", "d"];
console.log(array.includes("b")); // true
console.log(array.includes("e")); // false

2. Using indexOf()

This methods returns the index of the value if it exists, else it returns -1.

let array = ["a", "b", "c", "d"];
console.log(array.indexOf("b")); // 1
console.log(array.indexOf("e")); // -1

5 array methods in JavaScript.

Murtaja Ziad — Fri, 04 Dec 2020 11:00:00 +0000

Arrays are used to store multiple values in a single variable, and here’s 5 methods for them.

1. push()

push() method adds one or more elements to the end of an array and returns the new length of the array.

const animals = ["pigs", "goats", "sheep"];

const count = animals.push("cows");
console.log(count); // 4
console.log(animals); // ["pigs", "goats", "sheep", "cows"]

2. pop()

pop() method removes the last element from an array and returns that element. This method changes the length of the array.

const plants = ["broccoli", "cauliflower", "cabbage", "kale", "tomato"];

console.log(plants.pop()); // tomato
console.log(plants); // ["broccoli", "cauliflower", "cabbage", "kale"]

plants.pop();
console.log(plants); // ["broccoli", "cauliflower", "cabbage"]

3. shift()

shift() method removes the first element from an array and returns that removed element. This method changes the length of the array.

const array1 = [1, 2, 3];

const firstElement = array1.shift();
console.log(array1); // [2, 3]
console.log(firstElement); // 1

4. reverse()

reverse() method reverses an array in place. The first array element becomes the last, and the last array element becomes the first be careful, as it changes the original array.

const array1 = ["one", "two", "three"];
console.log(array1); // ["one", "two", "three"]

const reversed = array1.reverse();
console.log(reversed); // ["three", "two", "one"]
console.log(array1); // ["three", "two", "one"]

5. find()

find() method returns the value of the first element in the provided array that satisfies the provided testing function.

const array1 = [5, 12, 8, 130, 44];
const found = array1.find(element => element > 10);

console.log(found); // 12

How to create a clock using JavaScript?

Murtaja Ziad — Fri, 04 Dec 2020 11:00:00 +0000

In the beginning, create a new HTML, CSS & JavaScript file..

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Clock using JavaScript</title>
    <link rel="stylesheet" href="style.css" />
    <script src="app.js" defer></script>
  </head>
  <body></body>
</html>

Then, put a h2 with three span with the ID hours, minutes and seconds..

<h2>
  <span id="hours">00</span> : <span id="minutes">00</span> :
  <span id="seconds">00</span>
</h2>

Now, it will look like this..

Add some basic styling with a background..

body {
  padding: 0;
  margin: 0;
  box-sizing: border-box;

  min-height: 100vh;

  background-image: url("https://images.unsplash.com/photo-1605364441002-c1dbf7d9c7f1?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&q=100");
  background-repeat: no-repeat;
  background-position: center 40%;

  display: flex;
  align-items: center;
  justify-content: center;
}

h2 {
  font-size: 7rem;
  color: white;
}

It will look like this..

After that, create the main function which will get the time and put it into the spans

// Define the hours, minutes & seconds elements.
const hoursEl = document.getElementById("hours");
const minutesEl = document.getElementById("minutes");
const secondsEl = document.getElementById("seconds");

function main() {
  const totalSeconds = new Date().getTime() / 1000;

  const hours = Math.floor(totalSeconds / 3600) % 24;
  const minutes = Math.floor(totalSeconds / 60) % 60;
  const seconds = Math.floor(totalSeconds) % 60;

  hoursEl.innerText = formatTime(hours);
  minutesEl.innerText = formatTime(minutes);
  secondsEl.innerText = formatTime(seconds);
}

// Format the time by adding 0 before the time if it's less than 10..
function formatTime(time) {
  return time < 10 ? `0${time}` : time;
}

// Initial call.
main();

// Call the function every second.
setInterval(main, 1000);

and yeah, now it’s working..

5 string methods in JavaScript.

Murtaja Ziad — Fri, 27 Nov 2020 11:00:00 +0000

Strings are useful for holding data that can be represented in text form, and here’s 5 methods for them.

1. includes()

includes() method determines whether one string may be found within another string, returning true or false.

const sentence = "The quick brown fox jumps over the lazy dog.";

const word = "fox";

console.log(
  `The word "${word}" ${
    sentence.includes(word) ? "is" : "is not"
  } in the sentence.`
); // The word "fox" is in the sentence.

2. replace()

replace() method returns a new string with some or all matches of a pattern replaced by a replacement. The pattern can be a string or a RegExp, and the replacement can be a string or a function to be called for each match. If pattern is a string, only the first occurrence will be replaced.

const p =
  "The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?";
const regex = /dog/gi;

console.log(p.replace(regex, "ferret")); // The quick brown fox jumps over the lazy ferret. If the ferret reacted, was it really lazy?

console.log(p.replace("dog", "monkey")); // The quick brown fox jumps over the lazy monkey. If the dog reacted, was it really lazy?

3. split()

split() method divides a String into an ordered list of substrings, puts these substrings into an array, and returns the array.

const str = "The quick brown fox jumps over the lazy dog.";

const words = str.split(" ");
console.log(words[3]); // fox

const chars = str.split("");
console.log(chars[8]); // k

4. startsWith()

startsWith() method determines whether a string begins with the characters of a specified string, returning true or false as appropriate.

const str = "Saturday night plans";

console.log(str.startsWith("Sat")); // true

5. trim()

trim() method removes whitespace from both ends of a string. Whitespace in this context is all the whitespace characters (space, tab, no-break space, etc.) and all the line terminator characters (LF, CR, etc.).

const greeting = " Hello world! ";

console.log(greeting); // " Hello world! "
console.log(greeting.trim()); // "Hello world!"

8 useful console methods in JavaScript.

Murtaja Ziad — Fri, 20 Nov 2020 11:00:00 +0000

In this article, I will show you 8 useful console methods.

1. console.log

console.log() is used to output a message to the console, the message can be a string, a number, an array, an object, or a JavaScript expression.

console.log(1); // number.
console.log("hi"); // string.
console.log([1, 2, 3]); // array.
console.log({ hi: "bye" }); // object.
console.log(10 + 20); // expression.

2. console.assert

console.assert() writes the error message to the console only when the assertion is false.

console.assert(false, "The statement is false");
console.assert(50 > 100, "50 isn't bigger than 100");

3. console.clear

console.clear() clears the console only if it’s allowed by the environment.

console.clear();

4. console.dir

console.dir() displays an interactive list of the properties of the specified JavaScript object.

console.dir(document.location);

5. console.error

console.error() is used to display an error to the console.

console.error("A simple error.");

6. console.count

console.count() logs the number of times that this particular call to count() has been called.

for (let i = 0; i < 10; i++) {
  console.count("number");
}

7. console.table

console.table() is used to display data in the form of a table.

let object = {
  a: "hi",
  b: "hello",
  c: "bye",
};

console.table(object);

8. console.time

console.time() tracks how long an operation takes.

console.time("loop");
for (let i = 0; i < 10000; i++) {}
console.timeEnd("loop");

How to generate a local SSL certificate?

Murtaja Ziad — Fri, 13 Nov 2020 11:00:00 +0000

These commands has been tested in linux.

In the project root folder, run

openssl req -x509 -newkey rsa:2048 -keyout keytmp.pem -out cert.pem -days 365

Then run:

openssl rsa -in keytmp.pem -out key.pem

Now, you should have cert.pem and ket.pem in the project root folder.

If you’re using Node.JS/Express, you can load the certificate and key using:

const express = require("express");
const https = require("https");

const app = express();

app.get("/", (req, res) => {
  res.json({
    message: "Hello",
  });
});

https
  .createServer(
    {
      key: fs.readFileSync("key.pem"),
      cert: fs.readFileSync("cert.pem"),
    },
    app
  )
  .listen(3000, () => {
    console.log("Listening..");
  });

or if you are using create-react-app modify the start script in package.json:

"start": "export HTTPS=true&&SSL_CRT_FILE=cert.pem&&SSL_KEY_FILE=key.pem react-scripts start",

or using Gatsby:

gatsby develop --https --key-file ./key.pem --cert-file ./cert.pem