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//// [narrowingUnionToUnion.ts]
type Falsy = false | 0 | 0n | '' | null | undefined;
declare function isFalsy(value: unknown): value is Falsy;
function fx1(x: string | number | undefined) {
if (isFalsy(x)) {
x; // "" | 0 | undefined
}
}
function fx2<T>(x: T | undefined) {
if (isFalsy(x)) {
x; // T & Falsy | undefined
}
}
function fx3<T extends string | number>(x: T) {
if (isFalsy(x)) {
x; // T & "" | T & 0
}
}
declare function isA(obj: unknown): obj is { a: false } | { b: 0 };
function fx4(obj: { b: number }) {
if (isA(obj)) {
obj; // { b: 0 }
}
}
declare class X { x: string }
declare class XS extends X { xs: string }
declare class Y { y: string }
declare class YS extends Y { ys: string }
declare function isXSorY(obj: unknown): obj is XS | Y;
function fx5<T extends X>(obj: X | YS, c: typeof XS | typeof Y) {
if (obj instanceof c) {
obj; // XS | YS
}
if (isXSorY(obj)) {
obj; // XS | YS
}
}
// Repro from #31156
declare function isEmptyStrOrUndefined(mixed: any): mixed is "" | undefined;
function fx10(s: string | undefined) {
if (isEmptyStrOrUndefined(s)) {
s; // "" | undefined
if (s == undefined) {
s; // undefined
}
else {
s; // ""
}
}
}
// Repro from #37807
function f1(x: any): asserts x is number | undefined { }
let v1: number | string | undefined;
f1(v1);
v1; // number | undefined
function f2(x: any): asserts x is 6 | undefined { }
let v2: number | string | undefined;
f2(v2);
v2; // 6 | undefined
// #39105
declare function isEmptyString(value: string): value is '';
declare function isMaybeEmptyString(value: string | null | undefined): value is '' | null | undefined;
declare function isZero(value: number): value is 0;
declare function isMaybeZero(value: number | null | undefined): value is 0 | null | undefined;
declare function isEmptyArray<T>(value: T[]): value is [];
declare function isMaybeEmptyArray<T>(value: T[] | null | undefined): value is [] | null | undefined;
const TEST_CASES = [
(value: string) => {
if (isEmptyString(value)) {
value; // ""
}
else {
value; // string
}
if (isMaybeEmptyString(value)) {
value; // ""
}
else {
value; // string
}
},
(value?: string) => {
if (isMaybeEmptyString(value)) {
value; // "" | undefined
}
else {
value; // string
}
},
(value: number) => {
if (isZero(value)) {
value; // 0
}
else {
value; // number
}
if (isMaybeZero(value)) {
value; // 0
}
else {
value; // number
}
},
(value?: number) => {
if (isMaybeZero(value)) {
value; // 0 | undefined
}
else {
value; // number
}
},
(value: string[]) => {
if (isEmptyArray(value)) {
value; // []
}
else {
value; // string[]
}
if (isMaybeEmptyArray(value)) {
value; // []
}
else {
value; // string[]
}
},
(value?: string[]) => {
if (isMaybeEmptyArray(value)) {
value; // [] | undefined
}
else {
value; // string[]
}
},
];
// Repro from #42101
type EmptyString = '' | null | undefined;
function isEmpty(value: string | EmptyString): value is EmptyString {
return value === '' || value === null || value === undefined;
}
let test: string | null | undefined;
if (isEmpty(test)) {
test; // EmptyString
}
// Repro from #43825
declare function assert<T>(value: any): asserts value is T
function test1(foo: number | string | boolean) {
assert<1 | string>(foo);
foo; // string | 1
}
// Repro from #46909
function check1(x: unknown): x is (string | 0) {
return typeof x === "string" || x === 0;
}
function check2(x: unknown): x is ("hello" | 0) {
return x === "hello" || x === 0;
}
function test3(x: unknown) {
if (typeof x === "string" || x === 0) {
x; // string | 0
if (x === "hello" || x === 0) {
x; // 0 | "hello"
}
}
if (check1(x)) {
x; // string | 0
if (check2(x)) {
x; // 0 | "hello"
}
}
}
// Repro from #49588
function assertRelationIsNullOrStringArray(v: (string | number)[] | null): asserts v is string[] | null {}
function f1x(obj: (string | number)[] | null) {
assertRelationIsNullOrStringArray(obj);
obj; // string[] | null
}
//// [narrowingUnionToUnion.js]
"use strict";
function fx1(x) {
if (isFalsy(x)) {
x; // "" | 0 | undefined
}
}
function fx2(x) {
if (isFalsy(x)) {
x; // T & Falsy | undefined
}
}
function fx3(x) {
if (isFalsy(x)) {
x; // T & "" | T & 0
}
}
function fx4(obj) {
if (isA(obj)) {
obj; // { b: 0 }
}
}
function fx5(obj, c) {
if (obj instanceof c) {
obj; // XS | YS
}
if (isXSorY(obj)) {
obj; // XS | YS
}
}
function fx10(s) {
if (isEmptyStrOrUndefined(s)) {
s; // "" | undefined
if (s == undefined) {
s; // undefined
}
else {
s; // ""
}
}
}
// Repro from #37807
function f1(x) { }
var v1;
f1(v1);
v1; // number | undefined
function f2(x) { }
var v2;
f2(v2);
v2; // 6 | undefined
var TEST_CASES = [
function (value) {
if (isEmptyString(value)) {
value; // ""
}
else {
value; // string
}
if (isMaybeEmptyString(value)) {
value; // ""
}
else {
value; // string
}
},
function (value) {
if (isMaybeEmptyString(value)) {
value; // "" | undefined
}
else {
value; // string
}
},
function (value) {
if (isZero(value)) {
value; // 0
}
else {
value; // number
}
if (isMaybeZero(value)) {
value; // 0
}
else {
value; // number
}
},
function (value) {
if (isMaybeZero(value)) {
value; // 0 | undefined
}
else {
value; // number
}
},
function (value) {
if (isEmptyArray(value)) {
value; // []
}
else {
value; // string[]
}
if (isMaybeEmptyArray(value)) {
value; // []
}
else {
value; // string[]
}
},
function (value) {
if (isMaybeEmptyArray(value)) {
value; // [] | undefined
}
else {
value; // string[]
}
},
];
function isEmpty(value) {
return value === '' || value === null || value === undefined;
}
var test;
if (isEmpty(test)) {
test; // EmptyString
}
function test1(foo) {
assert(foo);
foo; // string | 1
}
// Repro from #46909
function check1(x) {
return typeof x === "string" || x === 0;
}
function check2(x) {
return x === "hello" || x === 0;
}
function test3(x) {
if (typeof x === "string" || x === 0) {
x; // string | 0
if (x === "hello" || x === 0) {
x; // 0 | "hello"
}
}
if (check1(x)) {
x; // string | 0
if (check2(x)) {
x; // 0 | "hello"
}
}
}
// Repro from #49588
function assertRelationIsNullOrStringArray(v) { }
function f1x(obj) {
assertRelationIsNullOrStringArray(obj);
obj; // string[] | null
}
//// [narrowingUnionToUnion.d.ts]
type Falsy = false | 0 | 0n | '' | null | undefined;
declare function isFalsy(value: unknown): value is Falsy;
declare function fx1(x: string | number | undefined): void;
declare function fx2<T>(x: T | undefined): void;
declare function fx3<T extends string | number>(x: T): void;
declare function isA(obj: unknown): obj is {
a: false;
} | {
b: 0;
};
declare function fx4(obj: {
b: number;
}): void;
declare class X {
x: string;
}
declare class XS extends X {
xs: string;
}
declare class Y {
y: string;
}
declare class YS extends Y {
ys: string;
}
declare function isXSorY(obj: unknown): obj is XS | Y;
declare function fx5<T extends X>(obj: X | YS, c: typeof XS | typeof Y): void;
declare function isEmptyStrOrUndefined(mixed: any): mixed is "" | undefined;
declare function fx10(s: string | undefined): void;
declare function f1(x: any): asserts x is number | undefined;
declare let v1: number | string | undefined;
declare function f2(x: any): asserts x is 6 | undefined;
declare let v2: number | string | undefined;
declare function isEmptyString(value: string): value is '';
declare function isMaybeEmptyString(value: string | null | undefined): value is '' | null | undefined;
declare function isZero(value: number): value is 0;
declare function isMaybeZero(value: number | null | undefined): value is 0 | null | undefined;
declare function isEmptyArray<T>(value: T[]): value is [];
declare function isMaybeEmptyArray<T>(value: T[] | null | undefined): value is [] | null | undefined;
declare const TEST_CASES: (((value: string) => void) | ((value: number) => void) | ((value: string[]) => void))[];
type EmptyString = '' | null | undefined;
declare function isEmpty(value: string | EmptyString): value is EmptyString;
declare let test: string | null | undefined;
declare function assert<T>(value: any): asserts value is T;
declare function test1(foo: number | string | boolean): void;
declare function check1(x: unknown): x is (string | 0);
declare function check2(x: unknown): x is ("hello" | 0);
declare function test3(x: unknown): void;
declare function assertRelationIsNullOrStringArray(v: (string | number)[] | null): asserts v is string[] | null;
declare function f1x(obj: (string | number)[] | null): void;
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