advanced patterns When Using Array.reduce() with Nested Arrays in React State Management
I'm having trouble with I've searched everywhere and can't find a clear answer... I'm working on a personal project and I'm working with an scenario when using `Array.reduce()` to flatten a nested array that holds state in a React component. The data structure I'm working with is an array of objects, where each object contains a `tags` property that is itself an array of strings. My goal is to flatten these arrays into a single array of unique tag strings, but I'm seeing duplicates in the output. Below is an example of what I'm working with: ```javascript const initialState = [ { id: 1, tags: ['react', 'javascript'] }, { id: 2, tags: ['javascript', 'css'] }, { id: 3, tags: ['html', 'react'] } ]; const flattenedTags = initialState.reduce((acc, curr) => { return acc.concat(curr.tags); }, []); const uniqueTags = [...new Set(flattenedTags)]; console.log(uniqueTags); // Expected: ['react', 'javascript', 'css', 'html'] ``` However, when I log `flattenedTags`, I see `['react', 'javascript', 'javascript', 'css', 'html', 'react']`, which is as expected, but `uniqueTags` results in duplicates, showing `['react', 'javascript', 'css', 'html']`. This is correct, but I was actually expecting to see the output in the same order as they initially appeared in the array. I also tried using `Array.from(new Set(flattenedTags))` as an alternative to create the unique array, but the order still doesn’t reflect the sequence in which the tags were initially introduced. I've checked the specifications, and it seems like the `Set` should maintain insertion order, but I need to understand why my output isn’t as expected. Are there any best practices for ensuring the uniqueness while maintaining order in such cases? I'm using React 17 and ES6 features. Any insights would be greatly appreciated! I'm working on a API that needs to handle this. Any ideas what could be causing this? For context: I'm using Javascript on macOS. What's the best practice here? I'm developing on Windows 10 with Javascript.