A 'CSS reset' for TypeScript, improving types for common JavaScript API's
ce9db42: Added support for widening in Array.lastIndexOf, Array.indexOf, ReadonlyArray.lastIndexOf and ReadonlyArray.indexOf.
107dfc2: Changed the array.includes on readonly arrays to NOT be a type predicate. Before this change, this perfectly valid code would not behave correctly.
type Code = 0 | 1 | 2;
type SpecificCode = 0 | 1;
const currentCode: Code = 0;
// Create an empty list of subset type
const specificCodeList: ReadonlyArray<SpecificCode> = [];
// This will be false, since 0 is not in []
if (specificCodeList.includes(currentCode)) {
currentCode; // -> SpecificCode
} else {
// This branch will be entered, and ts will think z is 2, when it is actually 0
currentCode; // -> 2
}
Removing the type predicate brings ts-reset closer towards correctness.
4765413: author: @mefechoel
Added the Map.has rule.
Similar to .includes or Set.has(), Map.has() doesn't let you pass members that don't exist in the map's keys:
// BEFORE
const userMap = new Map([
["matt", 0],
["sofia", 1],
[2, "waqas"],
] as const);
// Argument of type '"bryan"' is not assignable to
// parameter of type '"matt" | "sofia" | "waqas"'.
userMap.has("bryan");
With the rule enabled, Map follows the same semantics as Set.
// AFTER
import "@total-typescript/ts-reset/map-has";
const userMap = new Map([
["matt", 0],
["sofia", 1],
[2, "waqas"],
] as const);
// .has now takes a string as the argument!
userMap.has("bryan");
set-has implementation by adding support to ReadonlySet.