Debounce Function

The Debounce function serves to mitigate the rapid triggering of a function due to a series of events. It achieves this by delaying the function's execution until a specified interval has passed without the event firing again. This function proves particularly beneficial in real-world applications to enhance performance by limiting function calls when a user is quickly interacting with buttons.

Consider the following JavaScript snippet illustrating how to implement a Debounce function:

function debounce(func, delay) {

let timeout;

return function() {

const context = this;

const args = arguments;

clearTimeout(timeout);

timeout = setTimeout(() => func.apply(context, args), delay);

};

}

In this example, the Debounce function generates a new function that calls the original function after a defined delay. If the function is invoked again before the timeout elapses, the call is postponed.

This function is particularly useful for updating webpage layouts during window resizing, preventing performance degradation caused by excessive function calls.

Here’s how you might utilize the Debounce function:

// Define the function that updates the layout

function updateLayout() {

// Update the layout...

}

// Create a debounced version of the function

const debouncedUpdateLayout = debounce(updateLayout, 250);

// Listen for window resize events and call the debounced function

window.addEventListener("resize", debouncedUpdateLayout);

In this scenario, the layout will be updated at most once every 250 milliseconds during window resizing.

Throttle Function

Similar to Debounce, the Throttle function controls how frequently a function can execute. Rather than preventing function calls entirely, it ensures that the function runs at consistent intervals, thus avoiding excessive invocations within a set timeframe.

Here’s how to implement a Throttle function:

function throttle(func, delay) {

let wait = false;

return (...args) => {

if (wait) {

return;

}

func(...args);

wait = true;

setTimeout(() => {

wait = false;

}, delay);

}

}

This Throttle function guarantees that a specified function is executed no more than once every X milliseconds, making it particularly valuable for managing layout updates during scrolling events.

Example usage:

// Define the function that updates the layout

function updateLayout() {

// Update the layout...

}

// Create a throttled version of the function

const throttledUpdateLayout = throttle(updateLayout, 250);

// Listen for window scroll events and call the throttled function

window.addEventListener("scroll", throttledUpdateLayout);

In this instance, the updateLayout function will only execute once every 250 milliseconds during scrolling.

Once Function

The Once function is designed to restrict a function’s execution to a single instance. This feature proves useful for event listeners, where functions may need to run only once.

Here’s how you can implement the Once function:

function once(func) {

let ran = false;

let result;

return function() {

if (ran) return result;

result = func.apply(this, arguments);

ran = true;

return result;

};

}

For example, if you have a function that sends a data request to a server, employing the Once function ensures that the request is not triggered multiple times due to repeated clicks.

Example implementation:

// Define the function that sends the request

function requestSomeData() {

// Send the request...

}

// Create a version of the function that can only be called once

const sendRequestOnce = once(requestSomeData);

// Listen for clicks on a button and call the "once" function

const button = document.querySelector("button");

button.addEventListener("click", sendRequestOnce);

With this setup, the requestSomeData function will only execute once, regardless of how many times the user clicks the button.

Memoize Function

The Memoize function is utilized to cache the results of a function, preventing the need to repeatedly execute computationally intensive routines with the same parameters.

Here’s the implementation of the Memoize function:

function memoize(func) {

const cache = new Map();

return function() {

const key = JSON.stringify(arguments);

if (cache.has(key)) {

return cache.get(key);

}

const result = func.apply(this, arguments);

cache.set(key, result);

return result;

};

}

This function effectively caches results based on the arguments provided, enabling instant retrieval when called again with the same inputs.

To visualize the benefits of the Memoize function, consider its application in calculating Fibonacci numbers:

// Define the function that performs the calculation

function fibonacci(n) {

if (n < 2)

return 1;

return fibonacci(n - 1) + fibonacci(n - 2);

}

// Create a memoized version of the function

const memoizedFibonacci = memoize(fibonacci);

// Call the memoized function with multiple input values

console.time('total')

console.time('sub1')

const result1 = memoizedFibonacci(30);

console.timeEnd('sub1')

console.time('sub2')

const result2 = memoizedFibonacci(29);

console.timeEnd('sub2')

console.time('sub3')

const result3 = memoizedFibonacci(30);

console.timeEnd('sub3')

console.timeEnd('total')

In this case, the memoized function significantly reduces computation time for repeated calls.

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Curry Function

Currying is an advanced technique in JavaScript that allows the creation of a new function by pre-filling some arguments of an existing one. This method enhances code readability and divides functions into smaller units of responsibility.

Here’s how you can implement a Curry function:

function curry(func, arity = func.length) {

return function curried(...args) {

if (args.length >= arity) return func(...args);

return function(...moreArgs) {

return curried(...args, ...moreArgs);

};

};

}

This Curry function generates a new function that can be invoked with fewer arguments initially, returning another function until all required parameters are provided.

For instance, consider a method for calculating the distance between two points:

// Define the function that calculates the distance between two points

function distance(x1, y1, x2, y2) {

return Math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2);

}

// Create a curried version of the function that only requires one of the points

const distanceFromOrigin = curry(distance, 3)(0, 0);

// Call the curried function with the other point

const d1 = distanceFromOrigin(1, 1);

const d2 = distanceFromOrigin(2, 2);

In this example, the distanceFromOrigin function requires only the coordinates of one point, enhancing usability.

Partial Function

The Partial function is akin to Currying, but it returns the result immediately rather than chaining further calls. This function takes an existing function and one or more input arguments, returning a new function that incorporates those arguments.

Here’s an example of the Partial function:

function partial(func, ...args) {

return function partiallyApplied(...moreArgs) {

return func(...args, ...moreArgs);

}

}

Consider a calculate function that requires multiple parameters:

// Define the function that calculates something

function calculate(x, y, z) {

return (x + y) * z

}

// Create a partially applied version of the function

const multiply10By = partial(calculate, 8, 2);

// Call the partially applied function

const result = multiply10By(5);

Here, the multiply10By function is created by partially applying the calculate function, enhancing clarity.

Pipe Function

The Pipe function allows you to chain multiple functions together, passing the output of one function as the input to the next. This is akin to the Unix pipe operator and uses the JavaScript reduce() method.

Here’s how to implement the Pipe function:

function pipe(...funcs) {

return function piped(...args) {

return funcs.reduce((result, func) => [func.call(this, ...result)], args)[0];

};

}

To illustrate its application, consider these three functions:

function addPrefix(str) {

return "prefix-" + str;

}

function addSuffix(str) {

return str + "-suffix";

}

function toUppercase(str) {

return str.toUpperCase();

}

// Create a piped function

const decorated = pipe(addPrefix, addSuffix, toUppercase);

// Call the piped function

const result = decorated("hello"); // Outputs: PREFIX-HELLO-SUFFIX

In this example, the decorated function applies all three transformations in a left-to-right sequence.

Compose Function

The Compose function operates similarly to Pipe, but it applies functions in the reverse order, utilizing reduceRight.

Here’s the implementation:

function compose(...funcs) {

return function composed(...args) {

return funcs.reduceRight((result, func) => [func.call(this, ...result)], args)[0];

};

}

Pick Function

The Pick function enables you to extract specific properties from an object, creating a new object composed of those selected properties.

Here’s how to implement the Pick function:

function pick(obj, keys) {

return keys.reduce((acc, key) => {

if (obj.hasOwnProperty(key)) {

acc[key] = obj[key];

}

return acc;

}, {});

}

This function efficiently creates a new object by iterating over the keys and checking their presence in the original object.

Example usage:

const obj = {

id: 1,

name: 'Paul',

password: '82ada72easd7',

role: 'admin',

};

const selected = pick(obj, ['name', 'website']);

Omit Function

The Omit function serves as the inverse of Pick, allowing you to remove specified properties from an existing object, thereby preventing over-fetching.

Here’s how to implement the Omit function:

function omit(obj, keys) {

return Object.keys(obj)

.filter(key => !keys.includes(key))

.reduce((acc, key) => {

acc[key] = obj[key];

return acc;

}, {});

}

This function generates a new object excluding the designated properties.

Example:

const obj = {

id: 1,

name: 'Paul',

job: 'Senior Engineer',

};

const selected = omit(obj, ['id']);

Zip Function

The Zip function combines multiple arrays into a single array of tuples, pairing elements at corresponding indices from each array.

Since JavaScript lacks a built-in Zip function, here’s how to implement it:

function zip(...arrays) {

const maxLength = Math.max(...arrays.map(array => array.length));

return Array.from({ length: maxLength }).map((_, i) => {

return Array.from({ length: arrays.length }, (_, j) => arrays[j][i]);

});

}

This function constructs a new array of arrays, where each subarray consists of elements from the original arrays.

Example:

const xCoordinates = [1, 2, 3, 4];

const yCoordinates = [5, 6, 7, 8];

const zCoordinates = [3, 6, 1, 7];

// Create a zipped array of points

const points = zip(xCoordinates, yCoordinates, zCoordinates);

console.log(points); // Outputs: [[1, 5, 3], [2, 6, 6], [3, 7, 1], [4, 8, 7]]