JavaScript Array Methods Cheat Sheet (2025 Update)

JavaScript arrays are powerful — but with so many methods, it’s easy to forget what’s what. Here’s a 2025-ready cheat sheet to bookmark. 🔖

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🔄 Transformation

• map() → Transform each element
• filter() → Keep elements that match a condition
• reduce() → Reduce array to single value
• flat() → Flatten nested arrays
• flatMap() → Map + flatten in one step

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🔍 Searching

• find() → First element matching condition
• findIndex() → Index of first match
• includes() → Check if array contains a value
• indexOf() → First index of a value
• lastIndexOf() → Last index of a value

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✂️ Adding & Removing

• push() → Add to end
• pop() → Remove from end
• shift() → Remove from start
• unshift() → Add to start
• splice() → Add/remove anywhere

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🧹 Utility

• forEach() → Loop through elements
• every() → Check if all elements match condition
• some() → Check if at least one matches
• sort() → Sort elements (watch out for lexicographic sort!)
• reverse() → Reverse array

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🆕 2025+ Additions

• toSorted() → Immutable sort (doesn’t mutate original array)
• toReversed() → Immutable reverse
• toSpliced() → Immutable splice
• with() → Immutable element replacement

js
const arr = [1, 2, 3];
const newArr = arr.with(1, 99); 
// [1, 99, 3] → arr stays unchanged

Comments

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