5961ed7154
• A type guard of the form x instanceof C, where C is of a subtype of the global type ‘Function’ and C has a property named ‘prototype’ o when true, narrows the type of x to the type of the ‘prototype’ property in C provided it is a subtype of the type of x, or o when false, has no effect on the type of x.
74 lines
2.3 KiB
JavaScript
74 lines
2.3 KiB
JavaScript
//// [typeGuardOfFormInstanceOf.ts]
|
|
// A type guard of the form x instanceof C, where C is of a subtype of the global type 'Function'
|
|
// and C has a property named 'prototype'
|
|
// - when true, narrows the type of x to the type of the 'prototype' property in C provided
|
|
// it is a subtype of the type of x, or
|
|
// - when false, has no effect on the type of x.
|
|
|
|
class C1 {
|
|
p1: string;
|
|
}
|
|
class C2 {
|
|
p2: number;
|
|
}
|
|
class D1 extends C1 {
|
|
p3: number;
|
|
}
|
|
var str: string;
|
|
var num: number;
|
|
var strOrNum: string | number;
|
|
|
|
var c1Orc2: C1 | C2;
|
|
str = c1Orc2 instanceof C1 && c1Orc2.p1; // C1
|
|
num = c1Orc2 instanceof C2 && c1Orc2.p2; // C2
|
|
str = c1Orc2 instanceof D1 && c1Orc2.p1; // D1
|
|
num = c1Orc2 instanceof D1 && c1Orc2.p3; // D1
|
|
|
|
var c2Ord1: C2 | D1;
|
|
num = c2Ord1 instanceof C2 && c2Ord1.p2; // C2
|
|
num = c2Ord1 instanceof D1 && c2Ord1.p3; // D1
|
|
str = c2Ord1 instanceof D1 && c2Ord1.p1; // D1
|
|
var r2: D1 | C2 = c2Ord1 instanceof C1 && c2Ord1; // C2 | D1
|
|
|
|
//// [typeGuardOfFormInstanceOf.js]
|
|
// A type guard of the form x instanceof C, where C is of a subtype of the global type 'Function'
|
|
// and C has a property named 'prototype'
|
|
// - when true, narrows the type of x to the type of the 'prototype' property in C provided
|
|
// it is a subtype of the type of x, or
|
|
// - when false, has no effect on the type of x.
|
|
var __extends = this.__extends || function (d, b) {
|
|
for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
|
|
function __() { this.constructor = d; }
|
|
__.prototype = b.prototype;
|
|
d.prototype = new __();
|
|
};
|
|
var C1 = (function () {
|
|
function C1() {
|
|
}
|
|
return C1;
|
|
})();
|
|
var C2 = (function () {
|
|
function C2() {
|
|
}
|
|
return C2;
|
|
})();
|
|
var D1 = (function (_super) {
|
|
__extends(D1, _super);
|
|
function D1() {
|
|
_super.apply(this, arguments);
|
|
}
|
|
return D1;
|
|
})(C1);
|
|
var str;
|
|
var num;
|
|
var strOrNum;
|
|
var c1Orc2;
|
|
str = c1Orc2 instanceof C1 && c1Orc2.p1; // C1
|
|
num = c1Orc2 instanceof C2 && c1Orc2.p2; // C2
|
|
str = c1Orc2 instanceof D1 && c1Orc2.p1; // D1
|
|
num = c1Orc2 instanceof D1 && c1Orc2.p3; // D1
|
|
var c2Ord1;
|
|
num = c2Ord1 instanceof C2 && c2Ord1.p2; // C2
|
|
num = c2Ord1 instanceof D1 && c2Ord1.p3; // D1
|
|
str = c2Ord1 instanceof D1 && c2Ord1.p1; // D1
|
|
var r2 = c2Ord1 instanceof C1 && c2Ord1; // C2 | D1
|