What are the differences between JavaScript's for...in and for...of loops when iterating over an array?
Benjamin C

Thefor...in andfor...of loops are both used for iterating over elements in JavaScript, but they have distinct differences when it comes to iterating over an array. Thefor...in loop: - Thefor...in loop iterates over the enumerable properties of an object, including inherited properties. In the context of an array, it iterates over the indices (keys) of the array rather than the actual elements. - Example:

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  const array = [1, 2, 3];
  for (let index in array) {
    console.log(index); // Output: 0, 1, 2
  }

In this example, thefor...in loop iterates over the indices0,1, and2 of thearray, outputting each index value. Thefor...of loop: - Thefor...of loop is specifically designed for iterating over iterable objects, including arrays. It provides a simpler syntax for accessing the elements directly, without needing to deal with indices. - Example:

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  const array = [1, 2, 3];
  for (let element of array) {
    console.log(element); // Output: 1, 2, 3
  }

In this example, thefor...of loop iterates over each element in thearray, outputting each element value. Key differences: 1. Iterated Values: -for...in: Iterates over the indices (keys) of the array. -for...of: Iterates over the actual elements of the array. 2. Order of Iteration: -for...in: Does not guarantee the order of iteration. It may iterate over the properties in any order, as the properties of an object do not have an inherent order. -for...of: Maintains the order of iteration based on the indices of the array. It guarantees that the elements will be iterated in the same order as they appear in the array. 3. Accessing Values: -for...in: Requires additional access to the array using the index. The value can be accessed usingarray[index]. -for...of: Provides direct access to the element value without needing to reference the array by index. 4. Inherited Properties: -for...in: Iterates over all enumerable properties, including inherited properties. -for...of: Only iterates over the elements in the array and does not consider any inherited properties. In general, thefor...of loop is preferred for iterating over arrays as it provides a cleaner syntax and ensures the elements are accessed directly without needing to deal with indices. However, if you need to iterate over the properties of an object or require access to indices, thefor...in loop can be useful.

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