JavaScript recipes

Filter, sort, group, dedupe, chunk and transform arrays.

• Append one array to anotherHow to Extend Arrays in JavaScript
• Break out of forEachHow to Break from a JavaScript ForEach Loop
• Calculate the average of an arrayHow to Calculate Average of an Array in JavaScript
• Check if an array is emptyHow to Check if an Array is Empty in JavaScript
• Clone an arrayHow to Clone Arrays in JavaScript
• Count occurrences in an arrayHow to Count Elements with JavaScript
• Create an array of a given lengthHow to Create Arrays with a Specific Length in JavaScript
• Get the last element (index -1)How to Access -1 Index in JavaScript Arrays

Read, merge, copy and iterate over object properties.

• Access object propertiesHow to Access Object Properties in JavaScript
• Add a property to an objectHow to Add Properties to Objects in JavaScript
• Check if an object has a propertyHow to Check if an Object Has a Property in JavaScript
• Count the keys in an objectHow to Determine the Length of a Dictionary in JavaScript
• Flatten a nested objectHow to Flatten Objects in JavaScript
• Loop over key-value pairsHow to Iterate over Key-Value Pairs in JavaScript
• Merge two objectsHow to Combine Two Objects in JavaScript
• Use a variable as an object keyHow to Use a Variable as a Key in JavaScript

Search, replace, trim, pad and convert strings.

• Case-insensitive includesHow to Perform Case-Insensitive Includes in JavaScript
• Check if a string contains a substringHow to Check if a String Contains a Substring in JavaScript
• Check if a string is emptyHow to Check for an Empty String in JavaScript
• Check if a string starts withHow to Check if a String Begins with in JavaScript
• Convert a string to camelCaseHow to Use CamelCase in JavaScript
• Escape quotes in a stringHow to Escape Quotes in JavaScript
• Extract numbers from a stringHow to Extract Numbers from Strings in JavaScript
• Find all occurrences of a substringHow to Find All Occurrences with JavaScript

Round, format, parse and validate numbers.

• Check if a value is a numberHow to Determine if a Value is a Number in JavaScript
• Convert a float to an integerHow to Convert Floats to Integers in JavaScript
• Format a number with commasHow to Format Numbers with Commas in JavaScript
• Pad a number with leading zerosHow to Zero Pad Numbers in JavaScript
• Random number between two valuesHow to Generate Random Numbers Between Two Numbers in JavaScript
• Round to 2 decimal placesHow to Round to 2 Decimal Places in JavaScript

Add, subtract, compare and format dates and timestamps.

• Add days to a dateHow to Perform Date Addition in JavaScript
• Add months to a dateHow to Add Months to Dates in JavaScript
• Convert a timestamp to a dateHow to Convert Timestamps to Dates in JavaScript
• Difference between two datesHow to Subtract Dates in JavaScript
• Format a dateHow to Format JavaScript Datetime
• Format a date as YYYY-MM-DDHow to Format Dates as yyyy-mm-dd in JavaScript
• Get the current yearHow to Get Current Year in JavaScript
• Sort an array of datesHow to Sort Dates in JavaScript

Select, create, move and update elements on the page.

• Change an image sourceHow to Change Image Source in JavaScript
• Get an element's textHow to Access JavaScript Text Content
• Move an element to another parentHow to Move Elements with JavaScript
• Print a single elementHow to Print DIVs with JavaScript
• Replace an element's contentHow to Replace DIV Content with JavaScript
• Set element width and heightHow to Set Sizes with JavaScript
• Set the background colourHow to Set Background Color with JavaScript
• Uncheck a checkboxHow to Uncheck Checkboxes with JavaScript

Listen for, dispatch and simulate browser events.

• Simulate a keypressHow to Simulate Keypress Events in JavaScript

Work with Map and Set collections.

• Get the size of a MapHow to Determine the Size of a Map in JavaScript
• Sort a MapHow to Sort Maps in JavaScript

Parse URLs, query strings and domains.

• Get the domain from a URLHow to Get the Domain from a URL in JavaScript
• Read URL query parametersHow to Extract URL Parameters with JavaScript

Read, parse and download files.

• Convert CSV to an arrayHow to Convert CSV to Array in JavaScript
• Download a file from a URLHow to Download Files from URLs with JavaScript
• Read a CSV fileHow to Read CSV Files in JavaScript

Viewport, clipboard, storage and other browser APIs.

• Get the viewport widthHow to Get Viewport Width in JavaScript
• Translate textHow to Translate Text with JavaScript

Operators, conditionals, scope and language basics.

• Check if a function existsHow to Check if a Function Exists in JavaScript
• Check if a variable is definedHow to Check if a Variable is Defined in JavaScript
• Exit a function earlyHow to Exit Functions in JavaScript
• Less than or equal toHow to Compare Values with Less Than or Equal to in JavaScript
• Shorthand if/else (ternary)How to Use Shorthand If-Else Statements in JavaScript
• Swap two variablesHow to Swap Two Variables in JavaScript
• What curly braces doHow to Use Curly Braces in JavaScript

import, export, ESM and CommonJS.

• Export multiple functionsHow to Export Multiple Functions in JavaScript

Print and inspect values while debugging.

• Print a variableHow to Print Variables in JavaScript
• Print an arrayHow to Print Arrays in JavaScript

Classic algorithms implemented in JavaScript.

• FactorialHow to Perform Factorialization in JavaScript
• Merge sortHow to Perform Merge Sort in JavaScript

Server-side scripts, processes and the file system.

• Reverse shell in Node.jsHow to Perform Reverse Shell in JavaScript