JavaScript Array Duplication: Slice() or For Loop – Which is Faster?

JavaScript Array Duplication: Slice vs. For Loop Performance

When working with arrays in JavaScript, duplication is a common operation. Two widely used methods for array duplication are the slice() method and a traditional for loop. But which approach is faster?

Slice() Method:

The slice() method creates a shallow copy of an array. It iterates through the original array and creates a new array element by element. This approach is relatively efficient and ensures that the new array is independent of the original.

For Loop:

A for loop can also be used to duplicate an array. In this approach, the loop iterates through the original array, creating a new array with the same length and populating it with the values from the original array.

Comparison:

Benchmarks conducted in July 2016 revealed that the performance difference between these two methods depends on the browser being used.

• Blink-based Browsers (e.g., Chrome, Opera): Slice() is significantly faster.
• Non-Blink Browsers (e.g., Firefox, Safari): A for loop is faster because Blink does not optimize slice() and concat() internally.

Additional Considerations:

It's important to note that both slice() and for loop only perform shallow copies. If the original array contains references to objects or other complex data structures, these references are copied, not the objects themselves. This means that any changes made to the cloned array are also reflected in the original array.

Conclusion:

In general, for Blink-based browsers, slice() is the faster option for array duplication. For non-Blink browsers, a for loop is preferable. When dealing with arrays containing primitives, both approaches perform well. However, for arrays with references to complex data, consider using a library or a more robust deep cloning technique.

The above is the detailed content of JavaScript Array Duplication: Slice() or For Loop – Which is Faster?. For more information, please follow other related articles on the PHP Chinese website!