I created an array using Array's from and fill functions. However, each array created by the two methods made the desired processing result different.

Please check the content of the question in the following code : Why is the end result different?

let a1 = Array.from(Array(5), () => []);
let a2 = Array(5).fill([]);

// both '[ [], [], [], [], [] ]'
console.log(a1);
console.log(a2);

// both '[]'
console.log(a1[0]);
console.log(a2[0]);

a1[0].push(1);
a2[0].push(1);

// but the result isbut 
console.log(a1); // [ [ 1 ], [], [], [], [] ] // I wanted results like this for both a1 and a2.
console.log(a2); // [ [ 1 ], [ 1 ], [ 1 ], [ 1 ], [ 1 ] ]