JavaScript: Initialize a two dimension array of given width and height and value

JavaScript fundamental (ES6 Syntax): Exercise-53 with Solution

Initialize 2D Array with Size and Value

Write a JavaScript program to initialize a two-dimensional array of given size and value.

• Use Array.from() and Array.prototype.map() to generate h rows where each is a new array of size w.
• Use Array.prototype.fill() to initialize all items with value val.
• Omit the last argument, val, to use a default value of null.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
// Define a function 'initialize_2D_Array' to create a 2D array with a specified width, height, and default value.
const initialize_2D_Array = (w, h, val = null) =>
  // Create an array with the specified height and map each element to an array with the specified width filled with the default value.
  Array.from({ length: h }).map(() => Array.from({ length: w }).fill(val));

// Test cases
console.log(initialize_2D_Array(2, 2, 0)); // Output: [ [ 0, 0 ], [ 0, 0 ] ]
console.log(initialize_2D_Array(3, 3, 3)); // Output: [ [ 3, 3, 3 ], [ 3, 3, 3 ], [ 3, 3, 3 ] ]

Output:

[[0,0],[0,0]]
[[3,3,3],[3,3,3],[3,3,3]]

Visual Presentation:

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-1-53 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that creates a two-dimensional array of given dimensions, filled with a specified value.
• Write a JavaScript function that initializes an m x n matrix with a default value using nested loops.
• Write a JavaScript program that generates a 2D array with dynamic size and populates each element with a function result.

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