eventReactive（）的初始状态(Initial state of eventReactive())

 Typescript使用类似ActionScript3的getter / setter语法。 
 
class foo {
    private _bar:boolean = false;
    get bar():boolean {
        return this._bar;
    }
    set bar(theBar:boolean) {
        this._bar = theBar;
    }
}
 
 这将产生这个Javascript，使用Ecmascript 5 Object.defineProperty（）功能。 
 
var foo = (function () {
    function foo() {
        this._bar = false;
    }
    Object.defineProperty(foo.prototype, "bar", {
        get: function () {
            return this._bar;
        },
        set: function (theBar) {
            this._bar = theBar;
        },
        enumerable: true,
        configurable: true
    });
    return foo;
})();
 
 所以要用， 
 
var myFoo = new foo();
if(myFoo.bar) {         // calls the getter
    myFoo.bar = false;  // calls the setter and passes false
}
 
 但是，为了完全使用它，您必须确保TypeScript编译器指向ECMAScript5。 如果您正在运行命令行编译器，请使用--target标志像这样; 
 
 tsc - 目标ES5 
 
 如果您使用的是Visual Studio，则必须编辑项目文件以将该标志添加到TypeScriptCompile构建工具的配置中。 你可以在这里看到： 

Typescript uses getter/setter syntax that is like ActionScript3. 
 
class foo {
    private _bar:boolean = false;
    get bar():boolean {
        return this._bar;
    }
    set bar(theBar:boolean) {
        this._bar = theBar;
    }
}
 
That will produce this Javascript, using the Ecmascript 5 Object.defineProperty() feature.
 
var foo = (function () {
    function foo() {
        this._bar = false;
    }
    Object.defineProperty(foo.prototype, "bar", {
        get: function () {
            return this._bar;
        },
        set: function (theBar) {
            this._bar = theBar;
        },
        enumerable: true,
        configurable: true
    });
    return foo;
})();
 
So to use it,
 
var myFoo = new foo();
if(myFoo.bar) {         // calls the getter
    myFoo.bar = false;  // calls the setter and passes false
}
 
However, in order to use it at all, you must make sure the TypeScript compiler targets ECMAScript5. If you are running the command line compiler, use --target flag like this;
 
tsc --target ES5
 
If you are using Visual Studio, you must edit your project file to add the flag to the configuration for the TypeScriptCompile build tool. You can see that here:
 
As @DanFromGermany suggests below, if your are simply reading and writing a local property like foo.bar = true, then having a setter and getter pair is overkill. You can always add them later if you need to do something, like logging, whenever the property is read or written.