Your Second JavaScript Course

Demonstrate how var hoists to the scope top and yields undefined before declaration, while function declarations hoist with their bodies, and that arguments act as variables with the lowest priority.

Explore how JavaScript functions are objects via the function constructor, inspect length and name, distinguish arguments from the arguments variable, and learn about caller and callee, plus arrow functions.

Explain how this behaves in methods versus functions, why set timeout callbacks lose context, and how to use bind, apply, and call to redirect this and enable currying of arguments.

Identify higher-order functions as those that take functions as arguments or return one. Apply currying, converting multi-argument functions into nested single-argument calls, to avoid duplicated computation and gain control.

Apply currying and closure to track a running total cost in the global scope, where a curry cost function returns a child function sharing the same total across invocations.

Learn how closures simulate block scope by returning an inner function from a parent function, enabling access to outer variables while keeping them protected, with anonymous function variants.

Discover the real-life application of closures by using function scope to replace let with var, creating three independent K variables.

Explore the syntax of arrow functions, a concise alternative to traditional functions. Assign them to variables, omit parentheses for one argument, and return values with optional braces and defaults.

Compare this in traditional functions and arrow functions, showing how arrow this inherits from an outer function defined with function, and when it points to window or global object.

Explore how arrow functions bind this in JavaScript: inherit in setTimeout but fail in forEach when resetting this to an object, revealing when they help and when they hinder.

Explore map basics: an enhanced key-value collection with insertion order, where values may duplicate but keys are unique, using the map constructor and set, get, has, delete, and clear.

Learn to iterate over maps in JavaScript with forEach and for...of. Use destructuring to access keys and values, and leverage keys, values, and entries for map iteration.

Explore the ES6 set data type, a unique-values collection that preserves insertion order and removes duplicates by converting arrays to sets with the set constructor and the add method.

Merge two arrays with the spread operator, remove duplicates via a set to form union. Filter list one against the other to get intersection, and invert conditions for difference.

Learn how symbols serve as unique property names in JavaScript, preventing naming collisions when extending objects, by invoking the symbol function (and not using new) with an optional string description.

Create and compare symbol values by invoking the symbol function, noting their uniqueness and optional descriptions; understand wrapper objects and symbol prototype in projects, and their use as property names.

Compare symbol and symbol for method: symbol for method returns a shared symbol by key, while symbol creates a new symbol each time.

Learn how to use a symbol as a property name in an object, including using square brackets, understanding non-enumerable properties, and retrieving symbol properties with get own property symbols.

Learn how well-known symbols enable for-of iteration in strings, arrays, maps, and sets via the symbol iterator, and how map.prototype options like entries, values, and keys determine the output.

Create a custom iterator that follows the iterable and iterator protocols, uses next and for of to capitalize each array value during iteration.

Explore how generator objects implement both the iterable and iterator protocols, using next and yield to control execution and preserve context, often with promises to simplify callbacks.

Convert a linear function into a generator with five yields to control tasks—user ID check, database connection, and more—using next, return, and throw to manage iteration and errors.

Explore how the next() method passes values into a generator by yielding to variables, and why first next cannot send a value, requiring extra yield to set brand and model.

Explore two generator functions and how yield and yield asterisk enable iterating strings, arrays, and a generator object, yielding fruit, vegetable, dairy from the first and values from the second.

Build a promise-based ajax program in native JavaScript by creating a myAjax function that resolves on status 200 and rejects otherwise, using then, catch, and finally to output JSON.

Learn how the thenable object interacts with resolve and reject to produce a success value for on fulfilled and a failure reason for on rejected, with finally executing after settlement.

Explore what happens when replacing the Promise constructor with Promise.resolve and Promise.reject, and use setTimeout to fulfill after two seconds, triggering then and catch.

Master handling multiple promises with race, allSettled, and all by processing an array of promises and retrieving value or reason for each settled result.

Explore using async and await with Axios to exchange data, replace then and catch with try and catch, and write concise code by prefixing functions with async and awaiting promises.

Explore how async/await controls a JavaScript promise and setTimeout to ensure the console logs output in order, requiring a resolve function and awaiting the callback.

Explore the reflect object in JavaScript, learning its 13 static methods as alternatives to built-in operators, including apply, has, deleteProperty, and construct, and how to re-point this without using new.

Explain how a proxy defines custom behavior for operations using a target and handler, with traps like get that can capitalize the engine and deny other properties.

Explore how the proxy get trap intercepts property access to create private properties, returning access denied for underscored names while preserving normal values for others.

Using the get method, the proxy set trap prevents resetting underscore ID and throws an error, while normal properties can reset and new properties trigger interception and capitalization.

Explore the has and deleteProperty traps to guard private properties by replacing in with reflect.has and preventing deletion of underscores-prefixed properties.

Explore proxy object prototypes, where inherited get and set traps cause unexpected results and underscore proto access issues, and use object defined property or reflect defined property for safe addition.

Explore how the defineProperty trap intercepts property additions on a proxy, manipulates descriptors, and uses Reflect to properly set writable, enumerable, and configurable attributes.

Explore how the apply trap in a proxy intercepts a function call, redefining the this value and argument list, and intercepting the call method.

Explore using the new operator with the construct trap and a proxy to intercept constructor calls, return an object, and create static properties via the new target, while capitalizing arguments.

discover how to create a revocable proxy with Proxy.revocable, returning a wrapper with a proxy and revoke method, and how revocation sets is revoked to true, making the proxy unusable.

Explore how ES6 proxy and reflect intercept read and write operations with a handler and getter/setter. See how a proxy can envelop an object and power two-way data binding.