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Binary Buffer with Uint8Array

Published at25 Jul 2026
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Write a JavaScript function that takes an array of numbers (0-255), creates a Uint8Array from them, modifies the first element, and returns the modified array as a plain array. Typed arrays provide a mechanism for accessing raw binary data in memory.

Uint8Array is a typed array that represents an array of 8-bit unsigned integers. Each element is a value between 0 and 255. Typed arrays were introduced in ES6 and are the foundation for Web APIs like WebGL, Canvas, Web Audio, and WebSocket binary data handling. They provide efficient memory access by storing elements in contiguous memory.

Typed arrays come in several flavors: Int8Array, Uint8Array, Uint8ClampedArray, Int16Array, Uint16Array, Int32Array, Uint32Array, Float32Array, and Float64Array. Each stores values in the specified bit width and format. Values outside the valid range are wrapped or clamped.

Time complexity is O(n) for creating a typed array from a regular array. Element access is O(1). Space complexity is O(n) bytes for the underlying ArrayBuffer. Typed arrays are a JavaScript-specific feature for low-level memory manipulation.

Edge cases include values outside the 0-255 range (truncated to lower 8 bits), empty array, very large arrays, and ensuring the typed array is converted back to a regular array for comparison.

Example Input & Output

Example 1
Input
([100,200,300]
Output
[255,200,44]
Explanation

300 wrapped to... 300 & 0xFF = 44

Example 2
Input
[255]
Output
[255]
Explanation

Single element already 255

Example 3
Input
[10,20,30]
Output
[255,20,30]
Explanation

First element changed to 255

Example 4
Input
[0,0,0]
Output
[255,0,0]
Explanation

First zero changed to 255

Example 5
Input
[]
Output
[]
Explanation

Empty array unchanged

Algorithm Flow

Recommendation Algorithm Flow for Binary Buffer with Uint8Array
Recommendation Algorithm Flow for Binary Buffer with Uint8Array

Solution Approach

function solution(nums) {
  var arr = new Uint8Array(nums);
  if (arr.length > 0) arr[0] = 255;
  return Array.from(arr);
}

Best Answers

javascript - Approach 1
function solution(nums) {
  var arr = new Uint8Array(nums);
  if (arr.length > 0) arr[0] = 255;
  return Array.from(arr);
}