Tutorials

Lodash _.defer() Function Method

Posted in lodash Tutorial

Updated on Mar 11, 2024

By Mari Selvan

👁️ 20 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the dynamic landscape of JavaScript development, managing asynchronous operations is a common challenge. Lodash, a powerful utility library, comes to the rescue with functions like _.defer(). This method allows developers to defer the execution of a function to the next event loop cycle, enhancing control over the timing of function invocation.

Understanding and leveraging _.defer() can contribute to more efficient and responsive code.

🧠 Understanding _.defer() Method

The _.defer() method in Lodash is designed to delay the execution of a function until the current call stack has cleared, effectively deferring its invocation. This is particularly useful for scenarios where you want a function to run asynchronously, avoiding blocking the main thread.

💡 Syntax

The syntax for the _.defer() method is straightforward:

syntax.js

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_.defer(func, [args])

func: The function to defer.
args (Optional): The arguments to pass to the deferred function.

📝 Example

Let's dive into a simple example to illustrate the usage of the _.defer() method:

example.js

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const _ = require('lodash');

function delayedFunction(message) {
    console.log(`Delayed Execution: ${message}`);
}

_.defer(delayedFunction, 'Hello, Lodash!');
// Output: (output will be logged in the next event loop cycle)

In this example, the delayedFunction is deferred using _.defer(), allowing the rest of the code to continue executing without waiting for the function to complete.

🏆 Best Practices

When working with the _.defer() method, consider the following best practices:

Asynchronous Execution:

Use _.defer() when you want to ensure that a function runs asynchronously, especially when dealing with operations that could potentially block the main thread.
example.js
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```
const asyncOperation = () => {
    // ... perform asynchronous task ...
};

_.defer(asyncOperation);
// Continue with other operations without waiting for asyncOperation to complete
```

Reducing Main Thread Blocking:

Employ _.defer() to move non-critical or time-consuming tasks to the background, reducing the risk of blocking the main thread and improving the overall responsiveness of your application.

example.js

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const timeConsumingTask = () => {
    // ... perform a time-consuming task ...
};

// Execute the time-consuming task in the background
_.defer(timeConsumingTask);
// Continue with other operations without waiting for timeConsumingTask to complete

Function with Arguments:

When deferring a function that requires arguments, pass the arguments as the second parameter to _.defer().

example.js

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function deferredFunctionWithArgs(arg1, arg2) {
    console.log(`Deferred Execution with Arguments: ${arg1}, ${arg2}`);
}

_.defer(deferredFunctionWithArgs, 'arg1Value', 'arg2Value');
// Output: (output will be logged in the next event loop cycle)

📚 Use Cases

UI Rendering:

Deferred execution is beneficial when updating the UI after a user action. Use _.defer() to ensure that the UI updates occur asynchronously, preventing delays in responsiveness.

example.js

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const updateUserInterface = () => {
    // ... update UI elements ...
};

// Trigger UI update after user action
_.defer(updateUserInterface);
// Continue with other user interactions without waiting for the UI update to complete

Batch Processing:

When dealing with batch processing of data, _.defer() can be employed to process chunks of data in the background, avoiding interruptions to the main thread.

example.js

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const batchProcessData = (dataChunk) => {
    // ... process a chunk of data ...
};

const dataToProcess = /* ... fetch data ... */;
// Process data in the background in batches
dataToProcess.forEach(chunk => _.defer(batchProcessData, chunk));
// Continue with other operations without waiting for data processing to complete

Timed Execution:

Use _.defer() in combination with timers to create delays in function execution, achieving timed asynchronous behavior.

example.js

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const delayedLog = () => {
    console.log('Logged after a delay');
};

// Log after a delay of 1 second
setTimeout(() => {
    _.defer(delayedLog);
}, 1000);

🎉 Conclusion

The _.defer() method in Lodash provides a valuable tool for managing asynchronous operations in JavaScript. By deferring the execution of functions, you can optimize the responsiveness of your code, ensuring a smooth user experience and efficient handling of background tasks.

By adhering to best practices and exploring diverse use cases, you can harness the full potential of the _.defer() method in your Lodash projects.