Programming

Check/Validate String Matches Regex in JavaScript [Examples]

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JavaScript regex match

This article will show you how to use Regular Expressions (Regex) to validate matching strings in JavaScript. All user input collected in your applications should be validated. If an email address is required, a valid email address should be entered, or sending the email will fail. If a phone number is required, a valid phone number must be entered, and so on. Regex can be used for this validation by matching a whole string to a specified format. Regex can also be used to search … Read more

Simple Guide to Python Multiprocessing/Threading [Examples]

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Python multiprocessing

This article will provide a simple introduction to multiprocessing in Python and provide code examples. The code and examples in this article are for Python 3. Python 2 is no longer supported, if you are still using it you should be migrating your projects to the latest version of Python to ensure security and compatibility. What is Multiprocessing? Usually, Python runs your code, line-by-line, in a single process until it has completed. Multiprocessing allows you to run multiple sets of instructions simultaneously in separate processes, enabling your … Read more

Running External Programs in Python with subprocess [Examples]

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Python subprocess

This article will show you how to use the Python subprocess module to run external programs and scripts from Python. It is often necessary to call external applications from Python. Usually these are command-line applications which you can use to perform tasks outside of the Python environment, like manipulating files, or interacting with third party services. For example, you might call the wget command to retrieve a remote file. Any application which is accessible on the command line is available to subprocess, and can be executed from within Python. You … Read more

for…in Loops in JavaScript – How to Use Them

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JavaScript for...in loop

The for…in loop in JavaScript loops over all of the properties in an object. This article will explain why and how to use it. JavaScript Objects JavaScript objects are a kind of variable which store the properties for an item you are representing in your code. For example, you may have a car object, which of which the make, year, model, and colour of a car are it’s properties. Each car object would have it’s own separate list of properties which define that car. JavaScript objects can also be used as hash tables – providing … Read more

Remove Page Elements using JavaScript RemoveChild [Examples]

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JavaScript removeChild()

The Node.removeChild() method removes HTML Element from the current page via the DOM. This article will show you how to use it. The DOM in JavaScript The HTML DOM (Document Object Model) is the interface which JavaScript uses to interact with HTML page elements, including adding, removing, and modifying on-screen items. It is the data structure which represents every HTML tag present on a page – everything from the root <html> element that wraps the page to every <div>, <p>, <input>, and <span> – everything on the page is represented in the DOM, both … Read more

Use appendChild() in JavaScript to Add Page Elements [Examples]

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JavaScript appendChild()

The Node.appendChild() method adds a new HTML Element to the page (via the DOM). This article will show you how to use it. The DOM in JavaScript The HTML DOM (Document Object Model) is the interface which JavaScript uses to read from and interact with HTML page elements. It’s a data structure which represents every HTML tag present on the page – everything from the root <html> element that wraps your page to every <div>, <p>, <input>, and <em> – everything on the page is represented in the DOM, both content and structure. Each … Read more

Generate a Hash from String in Javascript, with Examples

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JavaScript Hash String

This tutorial will show you a practical way to generate a hash for a string in JavaScript, and provide working code examples you can use in your own project. What is a Hash? A Hash or Checksum is a calculated value with a specific length. By passing a hashing algorithm a string – which can be any length – a calculated hash of a consistent length is returned. Whenever the same string is passed to the hashing algorithm, the same calculated hash should be returned. … Read more

JavaScript setAttribute() Method-What It Is/How to Use It [Examples]

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JavaScript setAttribute()

JavaScript was built for adding interactivity to web pages. It can interact with and modify on-screen elements, including their HTML attributes – thats what setAttribute() does. Here’s how to use it. What is the HTML DOM? The HTML DOM (Document Object Model) is the interface which JavaScript uses to read from and interact with HTML page elements. It’s a data structure which represents every HTML tag present on the page – everything from the root <html> element that wraps your page to every <div>, <p>, <input>, and <em> – everything on the page is … Read more

Hash Tables/Associative Arrays in JavaScript – How and Why?

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JavaScript Hash Tables

JavaScript does not have a native object class called a “hash table” – but that doesn’t mean that the functionality of hash tables doesn’t exist in the language. Here’s how to use hash tables in JavaScript, with working example code. What is a Hash Table? Also known as hash maps, hash tables are a data structure which maps a list of keys to a list of corresponding values for each key. Any value in the table can be retrieved by accessing it through the associated key. … Read more

How to Generate the Fibonacci Sequence of Numbers in Python

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Python fibonacci sequence

This quick tutorial will show you how to generate the Fibonacci sequence of numbers in Python. This is a useful example for new coders and those just learning Python as it shows how variables, loops, and arithmetic are used in Python. What is the Fibonacci Sequence The Fibonacci sequence is a procession of numbers in which each number is the sum of the preceding two numbers. 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144… Above, the first 13 numbers in the Fibonacci … Read more