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//// [typeGuardsInConditionalExpression.ts]
// In the true expression of a conditional expression,
// the type of a variable or parameter is narrowed by any type guard in the condition when true,
// provided the true expression contains no assignments to the variable or parameter.
// In the false expression of a conditional expression,
// the type of a variable or parameter is narrowed by any type guard in the condition when false,
// provided the false expression contains no assignments to the variable or parameter.
function foo(x: number | string) {
return typeof x === "string"
? x.length // string
: x++; // number
}
function foo2(x: number | string) {
return typeof x === "string"
? ((x = "hello") && x) // string
: x; // number
}
function foo3(x: number | string) {
return typeof x === "string"
? ((x = 10) && x) // number
: x; // number
}
function foo4(x: number | string) {
return typeof x === "string"
? x // string
: ((x = 10) && x); // number
}
function foo5(x: number | string) {
return typeof x === "string"
? x // string
: ((x = "hello") && x); // string
}
function foo6(x: number | string) {
// Modify in both branches
return typeof x === "string"
? ((x = 10) && x) // number
: ((x = "hello") && x); // string
}
function foo7(x: number | string | boolean) {
return typeof x === "string"
? x === "hello" // boolean
: typeof x === "boolean"
? x // boolean
: x == 10; // boolean
}
function foo8(x: number | string | boolean) {
var b: number | boolean;
return typeof x === "string"
? x === "hello"
: ((b = x) && // number | boolean
(typeof x === "boolean"
? x // boolean
: x == 10)); // boolean
}
function foo9(x: number | string) {
var y = 10;
// usage of x or assignment to separate variable shouldn't cause narrowing of type to stop
return typeof x === "string"
? ((y = x.length) && x === "hello") // boolean
: x === 10; // boolean
}
function foo10(x: number | string | boolean) {
// Mixing typeguards
var b: boolean | number;
return typeof x === "string"
? x // string
: ((b = x) // x is number | boolean
&& typeof x === "number"
&& x.toString()); // x is number
}
function foo11(x: number | string | boolean) {
// Mixing typeguards
var b: number | boolean | string;
return typeof x === "string"
? x // string
: ((b = x) // x is number | boolean
&& typeof x === "number"
&& (x = 10) // assignment to x
&& x); // x is number
}
function foo12(x: number | string | boolean) {
// Mixing typeguards
var b: number | boolean | string;
return typeof x === "string"
? ((x = 10) && x.toString().length) // number
: ((b = x) // x is number | boolean
&& typeof x === "number"
&& x); // x is number
}
//// [typeGuardsInConditionalExpression.js]
// In the true expression of a conditional expression,
// the type of a variable or parameter is narrowed by any type guard in the condition when true,
// provided the true expression contains no assignments to the variable or parameter.
// In the false expression of a conditional expression,
// the type of a variable or parameter is narrowed by any type guard in the condition when false,
// provided the false expression contains no assignments to the variable or parameter.
function foo(x) {
return typeof x === "string"
? x.length // string
: x++; // number
}
function foo2(x) {
return typeof x === "string"
? ((x = "hello") && x) // string
: x; // number
}
function foo3(x) {
return typeof x === "string"
? ((x = 10) && x) // number
: x; // number
}
function foo4(x) {
return typeof x === "string"
? x // string
: ((x = 10) && x); // number
}
function foo5(x) {
return typeof x === "string"
? x // string
: ((x = "hello") && x); // string
}
function foo6(x) {
// Modify in both branches
return typeof x === "string"
? ((x = 10) && x) // number
: ((x = "hello") && x); // string
}
function foo7(x) {
return typeof x === "string"
? x === "hello" // boolean
: typeof x === "boolean"
? x // boolean
: x == 10; // boolean
}
function foo8(x) {
var b;
return typeof x === "string"
? x === "hello"
: ((b = x) && // number | boolean
(typeof x === "boolean"
? x // boolean
: x == 10)); // boolean
}
function foo9(x) {
var y = 10;
// usage of x or assignment to separate variable shouldn't cause narrowing of type to stop
return typeof x === "string"
? ((y = x.length) && x === "hello") // boolean
: x === 10; // boolean
}
function foo10(x) {
// Mixing typeguards
var b;
return typeof x === "string"
? x // string
: ((b = x) // x is number | boolean
&& typeof x === "number"
&& x.toString()); // x is number
}
function foo11(x) {
// Mixing typeguards
var b;
return typeof x === "string"
? x // string
: ((b = x) // x is number | boolean
&& typeof x === "number"
&& (x = 10) // assignment to x
&& x); // x is number
}
function foo12(x) {
// Mixing typeguards
var b;
return typeof x === "string"
? ((x = 10) && x.toString().length) // number
: ((b = x) // x is number | boolean
&& typeof x === "number"
&& x); // x is number
}
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