When working with arrays, prioritize clarity and explicitness over terse or clever constructs. For array membership checks, use `array.indexOf(item) === -1` rather than less obvious expressions like `!~array.indexOf(item)` or `array.indexOf(item) < 0`. This improves readability and makes code intent immediately clear to other developers. Be cautious with array manipulation methods that can cause unexpected behavior. The `.concat()` method can flatten arrays in unexpected ways: ```js // Potentially problematic: [key].concat(fns) // Will flatten if fns contains arrays // More predictable alternatives: [key, ...fns] // ES6 spread syntax preserves structure [].concat([key], fns) // More explicit nesting ``` These practices ensure that array operations behave predictably and their intention is clear to anyone reading the code, which is especially important for search and manipulation algorithms.