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