1. // matrix A
2. let matrixA = [
3.   [6, -2, -3],
4.   [-2, 5, -2],
5.   [-3, -2, 8],
6. ];
7.  
8.  
9. // Generate L and U using matrix A length
10. let matrixL = Array(matrixA.length)
11.   .fill()
12.   .map(() => Array(matrixA.length).fill(0));
13. let matrixU = Array(matrixA.length)
14.   .fill()
15.   .map(() => Array(matrixA.length).fill(0));
16.  
17. crout = () => {
18.   // assign matrix A length to a variable
19.   let n = matrixA.length;
20.  
21.   // loop in to index
22.   for (i = 0; i < n; i++) {
23.     for (j = 0; j < n; j++) {
24.       // if j is less than i change value of matrixL to 0 with its corresponding indexes
25.       if (j < i) matrixL[j][i] = 0;
26.  
27.       else {
28.         // the first column of matrix L is equal to the first column of matrix A
29.         matrixL[j][i] = matrixA[j][i];
30.         //  loop the values excluding the first column and top row
31.         for (k = 0; k < i; k++) {
32.           matrixL[j][i] = matrixL[j][i] - matrixL[j][k] * matrixU[k][i];
33.         }
34.       }
35.     }
36.     // loop in to index
37.     for (j = 0; j < n; j++) {
38.       // if j is less than i change value of martixU to 0 with its corresponding indexes
39.       if (j < i) matrixU[i][j] = 0;
40.       // if j is equal to i the change value to 1
41.       //  result to a diagonal values of 1
42.       else if (j == i) matrixU[i][j] = 1;
43.  
44.       else {
45.         // get index of the first rows of matrixU
46.         matrixU[i][j] = matrixA[i][j] / matrixL[i][i];
47.         // loop to get values excluding the first rows, 1's and 0's
48.         for (k = 0; k < i; k++) {
49.           matrixU[i][j] =
50.             matrixU[i][j] - (matrixL[i][k] * matrixU[k][j]) / matrixL[i][i];
51.         }
52.       }
53.     }
54.   }
55.   //  print in console
56.   console.log("matrixA:\n", matrixA, "\n\nmatrixL:\n", matrixL, "\n\nmatrixU:\n", matrixU);
57.  
58. };
59. crout();