JavaScript

"use strict";

Alternatively, you can enable strict mode for an individual function using the following syntax:

function myFunction() {
  "use strict";
  // Function code here
}

Enabling strict mode is generally recommended for all modern JavaScript code, as it promotes better coding practices, enhances code quality, and helps identify potential issues at an early stage of development. It also ensures greater compatibility with new ECMAScript features and future JavaScript versions.

console.log("Start");

function synchronousTask() {
  console.log("Task 1");
  console.log("Task 2");
  console.log("Task 3");
}

synchronousTask();

console.log("End");

In the example above, the output will be:

Start
Task 1
Task 2
Task 3
End

2. Asynchronous Code: Asynchronous code, on the other hand, allows tasks to be executed independently without blocking the main execution thread. Instead of waiting for a task to complete, asynchronous code initiates a task and moves on to the next line of code without waiting for the task to finish. When the task is completed, a callback function (or a promise in modern JavaScript) is invoked to handle the result of the asynchronous operation.

console.log("Start");

function asynchronousTask() {
  console.log("Task 1");

  // Simulate an asynchronous operation (e.g., API request, file reading)
  setTimeout(function () {
    console.log("Task 2");
  }, 2000);

  console.log("Task 3");
}

asynchronousTask();

console.log("End");

In the example above, the output will be:

Start
Task 1
Task 3
End
Task 2 (after a delay of 2 seconds)

As you can see, in the asynchronous code example, the “Task 2” message is printed after a delay of 2 seconds, while the rest of the code continues to execute.

Asynchronous code is crucial for tasks that may take some time to complete, such as making network requests, reading large files, or handling user input in web applications. By using asynchronous code, the program can remain responsive and continue to perform other tasks while waiting for the asynchronous operations to complete. This is especially important in web development, where it allows applications to provide a smooth user experience even when dealing with time-consuming tasks. Asynchronous patterns in JavaScript are typically implemented using callbacks, promises, and more recently, async/await syntax.

// Constructor function for creating Person objects
function Person(name, age) {
  this.name = name;
  this.age = age;
}

// Adding a method to the Person prototype
Person.prototype.sayHello = function() {
  console.log(`Hello, my name is ${this.name} and I'm ${this.age} years old.`);
};

// Creating instances of Person
const person1 = new Person("Alice", 30);
const person2 = new Person("Bob", 25);

person1.sayHello(); // Output: "Hello, my name is Alice and I'm 30 years old."
person2.sayHello(); // Output: "Hello, my name is Bob and I'm 25 years old."

In the example above, the `Person` constructor function is used to create two `person` objects (`person1` and `person2`). The `sayHello` method is defined on the prototype of the `Person` constructor using `Person.prototype`. Both `person1` and `person2` objects inherit the `sayHello` method from the `Person` prototype, thanks to the prototype chain.

Prototypes are powerful in JavaScript as they allow for efficient memory usage by sharing methods across multiple objects. They also provide a way to implement inheritance and create a hierarchy of objects with shared functionality. When used correctly, prototypes can lead to more efficient and maintainable code. However, with the introduction of ES6 classes, the syntax for working with prototypes has become more user-friendly, making it easier to implement object-oriented concepts in JavaScript.

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

numbers.forEach((num) =&gt; {
  console.log(num * 2);
});

// Output:
// 2
// 4
// 6
// 8

In this example, the `forEach()` method applies the callback function to each element in the `numbers` array and logs the result of multiplying each element by 2.

map() Method: The map() method is used to create a new array with the results of calling a provided function on every element in the original array. It returns a new array with the transformed elements, leaving the original array unchanged.

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

const doubledNumbers = numbers.map((num) =&gt; {
  return num * 2;
});

console.log(doubledNumbers); // Output: [2, 4, 6, 8]

In this example, the `map()` method applies the callback function to each element in the `numbers` array and creates a new array `doubledNumbers` containing the doubled values of the original elements.

Key Differences:

forEach() doesn’t return a new array; it only performs an action on each element in the original array.
map() returns a new array with the results of the provided function applied to each element in the original array.

In general, use `forEach()` when you want to perform some side effects on the elements of an array (e.g., logging, updating DOM), and use `map()` when you need to transform the elements of an array into a new array with modified values.

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Alternatively, you can enable strict mode for an individual function using the following syntax:

In the example above, the output will be:

In the example above, the output will be:

As you can see, in the asynchronous code example, the “Task 2” message is printed after a delay of 2 seconds, while the rest of the code continues to execute.

In this example, the `forEach()` method applies the callback function to each element in the `numbers` array and logs the result of multiplying each element by 2.

map() Method: The `map()` method is used to create a new array with the results of calling a provided function on every element in the original array. It returns a new array with the transformed elements, leaving the original array unchanged.

In this example, the `map()` method applies the callback function to each element in the `numbers` array and creates a new array `doubledNumbers` containing the doubled values of the original elements.

Key Differences:

`forEach()` doesn’t return a new array; it only performs an action on each element in the original array.

`map()` returns a new array with the results of the provided function applied to each element in the original array.

In general, use `forEach()` when you want to perform some side effects on the elements of an array (e.g., logging, updating DOM), and use `map()` when you need to transform the elements of an array into a new array with modified values.

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Related Topics

JAVASCRIPT

Alternatively, you can enable strict mode for an individual function using the following syntax:

In the example above, the output will be:

In the example above, the output will be:

As you can see, in the asynchronous code example, the “Task 2” message is printed after a delay of 2 seconds, while the rest of the code continues to execute.

In this example, the forEach() method applies the callback function to each element in the numbers array and logs the result of multiplying each element by 2.

map() Method: The map() method is used to create a new array with the results of calling a provided function on every element in the original array. It returns a new array with the transformed elements, leaving the original array unchanged.

In this example, the map() method applies the callback function to each element in the numbers array and creates a new array doubledNumbers containing the doubled values of the original elements.

Key Differences:

forEach() doesn’t return a new array; it only performs an action on each element in the original array.

map() returns a new array with the results of the provided function applied to each element in the original array.

In general, use forEach() when you want to perform some side effects on the elements of an array (e.g., logging, updating DOM), and use map() when you need to transform the elements of an array into a new array with modified values.

Click to Join:

Popular Category

Topics for You

Recent Posts

Categories

Programming

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Others

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In this example, the `forEach()` method applies the callback function to each element in the `numbers` array and logs the result of multiplying each element by 2.

map() Method: The `map()` method is used to create a new array with the results of calling a provided function on every element in the original array. It returns a new array with the transformed elements, leaving the original array unchanged.

In this example, the `map()` method applies the callback function to each element in the `numbers` array and creates a new array `doubledNumbers` containing the doubled values of the original elements.

`forEach()` doesn’t return a new array; it only performs an action on each element in the original array.

`map()` returns a new array with the results of the provided function applied to each element in the original array.

In general, use `forEach()` when you want to perform some side effects on the elements of an array (e.g., logging, updating DOM), and use `map()` when you need to transform the elements of an array into a new array with modified values.