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callbackHell.js
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callbackHell.js
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// callback hell is a situation where you have a lot of nested callbacks
// callback hell example:
setTimeout(() => {
console.log("start the callback hell");
setTimeout(() => {
console.log("first callback");
setTimeout(() => {
console.log("second callback");
setTimeout(() => {
console.log("third callback");
setTimeout(() => {
console.log("fourth callback");
setTimeout(() => {
console.log("fifth callback");
}, 1000);
}, 1000);
}, 1000);
}, 1000);
}, 1000);
console.log("End the callback hell");
}, 1000);
// =======================================================================
// Asynchronous function to retrieve user data from a remote server
function getUserData(userId, callback) {
setTimeout(() => {
const userData = { id: userId, name: "John Doe", age: 30 };
callback(userData);
}, 1000);
}
// Asynchronous function to retrieve user posts from a remote server
function getUserPosts(userId, callback) {
setTimeout(() => {
const userPosts = [
{ id: 1, title: "Post 1", body: "Body of post 1" },
{ id: 2, title: "Post 2", body: "Body of post 2" },
{ id: 3, title: "Post 3", body: "Body of post 3" },
];
callback(userPosts);
}, 2000);
}
// Asynchronous function to retrieve user comments from a remote server
function getUserComments(userId, callback) {
setTimeout(() => {
const userComments = [
{ id: 1, postId: 1, text: "Comment 1 for post 1" },
{ id: 2, postId: 1, text: "Comment 2 for post 1" },
{ id: 3, postId: 2, text: "Comment 1 for post 2" },
{ id: 4, postId: 2, text: "Comment 2 for post 2" },
{ id: 5, postId: 3, text: "Comment 1 for post 3" },
];
callback(userComments);
}, 3000);
}
// Asunchronous function to retrieve user reactions from a remote server
function getUserReactions(userId, callback) {
setTimeout(() => {
const userReactions = [
{ id: 1, postId: 1, text: "Reaction 1 for post 1" },
{ id: 2, postId: 1, text: "Reaction 2 for post 1" },
{ id: 3, postId: 2, text: "Reaction 1 for post 2" },
{ id: 4, postId: 2, text: "Reaction 2 for post 2" },
{ id: 5, postId: 3, text: "Reaction 1 for post 3" },
];
callback(userReactions);
}, 4000);
}
// Retrieve user data, posts, and comments and log them to the console
const userId = 123;
getUserData(userId, (userData) => {
console.log("User Data: ", userData);
getUserPosts(userId, (userPosts) => {
console.log("User Posts: ", userPosts);
getUserComments(userId, (userComments) => {
console.log("User Comments: ", userComments);
getUserReactions(userId, (userReactions) => {
console.log("User Reactions: ", userReactions);
});
});
});
});