83 lines
1.5 KiB
TypeScript
83 lines
1.5 KiB
TypeScript
|
|
class A {
|
|
propA: number;
|
|
}
|
|
|
|
class B {
|
|
propB: number;
|
|
}
|
|
|
|
class C extends A {
|
|
propC: number;
|
|
}
|
|
|
|
declare function isA(p1: any): p1 is A;
|
|
declare function isB(p1: any): p1 is B;
|
|
declare function isC(p1: any): p1 is C;
|
|
|
|
declare function retC(): C;
|
|
|
|
var a: A;
|
|
var b: B;
|
|
|
|
// Basic
|
|
if (isC(a)) {
|
|
a.propC;
|
|
}
|
|
|
|
// Sub type
|
|
var subType: C;
|
|
if(isA(subType)) {
|
|
subType.propC;
|
|
}
|
|
|
|
// Union type
|
|
var union: A | B;
|
|
if(isA(union)) {
|
|
union.propA;
|
|
}
|
|
|
|
// Call signature
|
|
interface I1 {
|
|
(p1: A): p1 is C;
|
|
}
|
|
|
|
// The parameter index and argument index for the type guard target is matching.
|
|
// The type predicate type is assignable to the parameter type.
|
|
declare function isC_multipleParams(p1, p2): p1 is C;
|
|
if (isC_multipleParams(a, 0)) {
|
|
a.propC;
|
|
}
|
|
|
|
// Methods
|
|
var obj: {
|
|
func1(p1: A): p1 is C;
|
|
}
|
|
class D {
|
|
method1(p1: A): p1 is C {
|
|
return true;
|
|
}
|
|
}
|
|
|
|
// Arrow function
|
|
let f1 = (p1: A): p1 is C => false;
|
|
|
|
// Function type
|
|
declare function f2(p1: (p1: A) => p1 is C);
|
|
|
|
// Function expressions
|
|
f2(function(p1: A): p1 is C {
|
|
return true;
|
|
});
|
|
|
|
// Evaluations are asssignable to boolean.
|
|
declare function acceptingBoolean(a: boolean);
|
|
acceptingBoolean(isA(a));
|
|
|
|
// Type predicates with different parameter name.
|
|
declare function acceptingTypeGuardFunction(p1: (item) => item is A);
|
|
acceptingTypeGuardFunction(isA);
|
|
|
|
// Binary expressions
|
|
let union2: C | B;
|
|
let union3: boolean | B = isA(union2) || union2; |