TypeScript Version: 2.3.4
Code
/*
tsconfig.json
{
"compilerOptions": {
"target": "ES2015",
"module": "commonjs",
"strict": true
}
}
*/
let maybeNumber = Math.random() > 0.5 ? 2 : null;
let ones = [1, 1, 1];
let twoes;
if (maybeNumber) {
twoes = ones.map(x => x * maybeNumber);
}
console.log(maybeNumber, twoes);Expected behavior:
Compilation passes, TS should know that .map function will be executed immediately and so maybeNumber will not be null
Actual behavior:
Compilation error: error TS2531: Object is possibly 'null'
Weird:
When I change let maybeNumber to const maybeNumber compilation passes for some reason, even though type of maybeNumber should be still number | null
TypeScript Version: 2.3.4
Code
Expected behavior:
Compilation passes, TS should know that .map function will be executed immediately and so
maybeNumberwill not benullActual behavior:
Compilation error:
error TS2531: Object is possibly 'null'Weird:
When I change
let maybeNumbertoconst maybeNumbercompilation passes for some reason, even though type ofmaybeNumbershould be stillnumber | null