What are the best practices for using for...in and for...of loops in JavaScript?

What are the best practices for using for...in and for...of loops in JavaScript?

When using for...in, it's best for iterating over object properties, but avoid it for arrays due to potential prototype issues. Use for...of for arrays and iterable objects, as it provides a cleaner syntax and avoids these pitfalls.

Can you give me an example of when to use each loop?

Sure! Use for...in when you want to loop through an object's keys, like this: for (let key in obj) { console.log(key); }. Use for...of for arrays, like this: for (let value of arr) { console.log(value); }.

What are the drawbacks of using for...in?

The main drawback is that for...in iterates over all enumerable properties, including those inherited from the prototype chain, which can lead to unexpected results.

Is there a performance difference between the two?

Yes, for...of is generally faster for arrays since it directly accesses the values, while for...in has to check each property, which can slow down performance.