Скачать или смотреть How to Optimize Your JavaScript Switch Statement: Check Variable Type vs Allow Execution

Discover the best approach to optimize your JavaScript switch statements when working with variables of different types. Learn whether to check for the variable type upfront or let the switch run.
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This video is based on the question https://stackoverflow.com/q/64020650/ asked by the user 'Caffeine' ( https://stackoverflow.com/u/13362918/ ) and on the answer https://stackoverflow.com/a/64020809/ provided by the user 'Pranav Rustagi' ( https://stackoverflow.com/u/14046126/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding JavaScript Switch Statements

When creating applications—like a chat bot for organizing schedules—developer efficiency is crucial. This could involve choosing the right approach to handle variables dynamically. One such scenario involves using a switch statement to map a weekday represented by various types (strings and integers) onto a predefined set of values.

In this post, we will explore two approaches in understanding the performance and efficiency of your switch statements in JavaScript. We will discuss:

Checking the variable type before execution

Allowing the switch statement to execute regardless of the variable type

The Scenario: Handling Weekday Variables

Imagine you’ve built a chat bot that takes user input to determine the current day of the week—this could be either:

An integer (0-6)

A string (e.g., "monday", "tuesday", etc.)

Your bot uses a variable called weekday to store this information. Depending on the user’s input, this variable could take on different forms.

Option 1: Checking the Variable Type

To optimize performance, many developers consider checking the variable’s type before executing the switch statement:

[[See Video to Reveal this Text or Code Snippet]]

Pros of this Approach:

Efficiency: This check prevents unnecessary execution of the switch statement when the variable is not a number. If the type isn’t a number, the execution stops right away, avoiding unnecessary computations.

Cons:

It requires an additional conditional check.

Option 2: Allowing the Switch to Execute

Alternatively, you can let the switch statement run without checking the variable type first:

[[See Video to Reveal this Text or Code Snippet]]

Pros of this Approach:

Simplicity: The code is straightforward and does not require an extra check.

Less Lines of Code: You avoid redundancy in checking the type beforehand.

Cons:

Performance Hit: If the variable is a string, the switch statement will check against all cases without making any changes, which can be slightly less efficient.

Which Approach is Faster?

To make a long story short, if you anticipate the potential of receiving a string value for weekday often, checking the type before executing the switch statement is generally the more efficient option.

Key Takeaways

Efficiency Matters: For good programming practices, especially in larger projects, optimizing code to avoid unnecessary execution should be a priority.

Context is Everything: Depending on how often you expect to receive different types of data, you may choose one method over the other based on your specific use case.

In conclusion, while both methods have merits, choosing to check the variable type creates a more robust and efficient code structure for applications that handle multiple input types.

So next time you're faced with a similar decision in JavaScript, remember that little adjustments can lead to significant improvements!