JavaScript
- Getting started with JavaScript
- Awesome Book
- Awesome Community
- Awesome Course
- Awesome Tutorial
- Awesome YouTube
- .postMessage() and MessageEvent
- AJAX
- Anti-patterns
- Arithmetic (Math)
- Arrays
- Append / Prepend items to Array
- Array comparison
- Array spread / rest
- Checking if an object is an Array
- Concatenating Arrays
- Convert a String to an Array
- Converting Array-like Objects to Arrays
- Copy part of an Array
- Destructuring an array
- Filtering Object Arrays
- Filtering values
- Finding the minimum or maximum element
- Flattening Arrays
- Insert an item into an array at a specific index
- Iteration
- Joining array elements in a string
- Logical connective of values
- Mapping values
- Merge two array as key value pair
- Object keys and values to array
- Reducing values
- Remove value from array
- Removing all elements
- Removing duplicate elements
- Removing items from an array
- Removing/Adding elements using splice()
- Reversing arrays
- Searching an Array
- Shallow cloning an array
- Sorting Arrays
- Sorting multidimensional array
- Standard array initialization
- Test all array items for equality
- The entries() method
- Using map to reformat objects in an array
- Arrow Functions
- Async functions (async/await)
- Async Iterators
- Automatic Semicolon Insertion - ASI
- Battery Status API
- Behavioral Design Patterns
- Binary Data
- Bitwise operators
- Bitwise Operators - Real World Examples (snippets)
- BOM (Browser Object Model)
- Built-in Constants
- Callbacks
- Classes
- Comments
- Comparison Operations
- Conditions
- Console
- Constructor functions
- Context (this)
- Cookies
- Creational Design Patterns
- Custom Elements
- Data attributes
- Data Manipulation
- Datatypes in Javascript
- Date
- Date Comparison
- Debugging
- Declarations and Assignments
- Destructuring assignment
- Detecting browser
- Enumerations
- Error Handling
- Escape Sequences
- Evaluating JavaScript
- Events
- execCommand and contenteditable
- Fetch
- File API, Blobs and FileReaders
- Fluent API
- Functional JavaScript
- Functions
- Generators
- Geolocation
- Global error handling in browsers
- History
- How to make iterator usable inside async callback function
- IndexedDB
- Inheritance
- Intervals and Timeouts
- JavaScript Variables
- JSON
- Linters - Ensuring code quality
- Localization
- Loops
- Map
- Memory efficiency
- Method Chaining
- Modals - Prompts
- Modularization Techniques
- Modules
- Namespacing
- Navigator Object
- Notifications API
- Objects
- Performance Tips
- Promises
- Prototypes, objects
- Proxy
- Regular expressions
- requestAnimationFrame
- Reserved Keywords
- Same Origin Policy & Cross-Origin Communication
- Scope
- Screen
- Security issues
- Selection API
- Server-sent events
- Set
- Setters and Getters
- Strict mode
- Strings
- Symbols
- Tail Call Optimization
- Template Literals
- The Event Loop
- Tilde ~
- Timestamps
- Transpiling
- Unary Operators
- Unit Testing Javascript
- Using javascript to get/set CSS custom variables
- Variable coercion/conversion
- Vibration API
- WeakMap
- WeakSet
- Web Cryptography API
- Web Storage
- WebSockets
- Workers
JavaScript Arrays Checking if an object is an Array
Example
Array.isArray(obj) returns true if the object is an Array, otherwise false.
Array.isArray([]) // true
Array.isArray([1, 2, 3]) // true
Array.isArray({}) // false
Array.isArray(1) // false
In most cases you can instanceof to check if an object is an Array.
[] instanceof Array; // true
{} instanceof Array; // false
Array.isArray has the an advantage over using a instanceof check in that it will still return true even if the prototype of the array has been changed and will return false if a non-arrays prototype was changed to the Array prototype.
var arr = [];
Object.setPrototypeOf(arr, null);
Array.isArray(arr); // true
arr instanceof Array; // false
