typescript TS - 只能使用“new”关键字调用 void 函数
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TS - Only a void function can be called with the 'new' keyword
提问by Alexander Mills
I am getting this weird error from TypeScript:
我从 TypeScript 收到这个奇怪的错误：
"Only a void function can be called with the 'new' keyword."
“只能使用 'new' 关键字调用 void 函数。”
What?
什么？
The constructor function, just looks like:
构造函数，看起来像：
function Suman(obj: ISumanInputs): void {
const projectRoot = _suman.projectRoot;
// via options
this.fileName = obj.fileName;
this.slicedFileName = obj.fileName.slice(projectRoot.length);
this.networkLog = obj.networkLog;
this.outputPath = obj.outputPath;
this.timestamp = obj.timestamp;
this.sumanId = ++sumanId;
// initialize
this.allDescribeBlocks = [];
this.describeOnlyIsTriggered = false;
this.deps = null;
this.numHooksSkipped = 0;
this.numHooksStubbed = 0;
this.numBlocksSkipped = 0;
}
I have no idea what the problem is. I tried adding and removing the return type (void) but that did nothing.
我不知道问题是什么。我尝试添加和删除返回类型（void），但没有任何作用。
采纳答案by Sean Vieira
The issue is that ISumanInputsdoes not include one or more of the properties that you're including in your call orthat you haven't properly fulfilled the IsumanInputsinterface.
问题是ISumanInputs不包括您在调用中包含的一个或多个属性，或者您没有正确实现IsumanInputs接口。
In the extra property case you should get one "extra" error:
在额外的财产情况下，你应该得到一个“额外”的错误：
Object literal may only specify known properties, and 'anExtraProp' does not exist in type 'ISumanInputs'
对象字面量只能指定已知属性，并且类型“ISumanInputs”中不存在“anExtraProp”
In the missing property case you will get a different "extra" error:
在缺少属性的情况下，您将收到不同的“额外”错误：
Property 'timestamp' is missing in type '{ fileName: string; networkLog: string; outputPath: string; }'.
类型“{ fileName: string;”中缺少属性“timestamp” 网络日志：字符串；输出路径：字符串；}'。
Interestingly enough, if you move the definition of the argument out of line the extra propertycase no longer fails:
有趣的是，如果您将参数的定义移出线外，额外的属性案例不再失败：
const data = {
fileName: "abc",
networkLog: "",
outputPath: "",
timestamp: "",
anExtraProperty: true
};
new Suman(data);
回答by Jokester
As Sean pointed out, this is a less obvious consequence of type mismatch in arguments.
正如肖恩所指出的，这是参数类型不匹配的一个不太明显的结果。
In case a deeper reason interests you: when arguments of a function don't typecheck, tscinfers return type to be a special type never(overriding voidyou specified). And newwith such a function will cause TS2350 Only a void function can....
如果您对更深层次的原因感兴趣：当函数的参数不进行tsc类型检查时，将返回类型推断为特殊类型never（覆盖void您指定的类型）。而new有了这样的功能就会造成TS2350 Only a void function can....
This snippet can trigger TS2350 without incorrect arguments.
此代码段可以在没有错误参数的情况下触发 TS2350。
function Ctor(): never {
throw "never return";
}
const v = new Ctor();
