Help needed with populating a binary matrix.
let binaryMatrix: number[][] = [];
for (let i = 0; i < 7; i++) {
for (let j = 0; j < 7; j++) {
if (!binaryMatrix[i]) binaryMatrix[i] = [];
if (!binaryMatrix[i][j]) binaryMatrix[i][j] = []; // triggering TS exception
binaryMatrix[i][j] = 1;
}
}
The statement binaryMatrix[i][j] = [] causes a TS exception -
Type 'never[]' is not assignable to type 'number'.ts(2322)Any suggestions on how to resolve this issue?
The issue arises from attempting to assign an empty array (never[]) to the variable number, which is causing the error that is mentioned. Given that your original matrix variable is a 2D array, the second check you have in place is unnecessary and can be removed.
const matrix: number[][] = [];
for (let i = 0; i < 7; i++) {
for (let j = 0; j < 7; j++) {
if (!matrix[i]) matrix[i] = [];
// This check is not needed and is invalid!
//if (!matrix[i][j]) matrix[i][j] = [];
matrix[i][j] = 1;
}
}
The reason why an empty array is considered to be of type never[] is due to its freshness. If it were a variable, like this:
const arr = []
// ^? -- any[]
it would be classified as any[]. However, when you explicitly add it to the array as an empty array, because it is fresh, it immediately takes on the true type at assignment: never[]
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