Question

问题

参数值maxORhealth会提示以下错误；在VS代码中：

Type 'undefined' is not assignable to type 'number'.ts(2345)

...并且不确定如何浏览此错误。

类定义

    class Vitals implements IVitals
    {
        vitals!: 
        { 
            HealthValue:    number | undefined; 
            StrengthValue?: number | undefined;
            ManaValue?:     number | undefined; 
            StaminaValue?:  number | undefined; 
            IntelectValue?: number | undefined; 
            TuneValue?:     number | undefined; 
        };

        /// CONSTRUCTORS
        constructor()
        constructor(maxORhealth: number)
        constructor(maxORhealth: number, maxORstrength: number)
        constructor(maxORhealth: number, 
                    maxORstrength: number, 
                    mana: number, 
                    stamina: number, 
                    intelect: number, 
                    tune: number)
        constructor(maxORhealth?: number, 
                    maxORstrength?: number, 
                    mana?: number, 
                    stamina?: number, 
                    intelect?: number, 
                    tune?: number)
    {
           if (Number.isInteger(maxORhealth) && maxORstrength === undefined && mana === undefined)
           {
                this.vitals.HealthValue   = getRandomInt(maxORhealth);  <= Error .ts(2345)
                this.vitals.StrengthValue = getRandomInt(maxORhealth);
                this.vitals.ManaValue     = getRandomInt(maxORhealth); 
                this.vitals.StaminaValue  = getRandomInt(maxORhealth); 
                this.vitals.IntelectValue = getRandomInt(maxORhealth); 
                this.vitals.TuneValue     = getRandomInt(maxORhealth); 
           }
           else if (Number.isInteger(maxORhealth) && maxORstrength === undefined)
           {
                this.vitals.HealthValue   = maxORhealth; 
                this.vitals.StrengthValue = getRandomInt(maxORstrength!);
                this.vitals.ManaValue     = getRandomInt(maxORstrength!); 
                this.vitals.StaminaValue  = getRandomInt(maxORstrength!); 
                this.vitals.IntelectValue = getRandomInt(maxORstrength!); 
                this.vitals.TuneValue     = getRandomInt(maxORstrength!); 
            }
            else
            {
                this.vitals.HealthValue   = maxORhealth; 
                this.vitals.StrengthValue = maxORstrength;
                this.vitals.ManaValue     = mana; 
                this.vitals.StaminaValue  = stamina; 
                this.vitals.IntelectValue = intelect; 
                this.vitals.TuneValue     = tune; 
            }
        }
    }

期望的影响

我希望本节课有三个constructors，如下所示：

    constructor()
    constructor(maxORhealth: number)
    constructor(maxORhealth: number, maxORstrength: number)
    constructor(maxORhealth: number, maxORstrength: number, mana: number, stamina: number, intelect: number, tune: number)

...（希望）有一个实用的（没有过多的JS花式）解决方案。

干杯，谢谢。

Answer 1

错误源自以下语句：

Number.isInteger(maxORhealth)

maxORhealth的类型为number | undefined。因为它是构造函数的可选参数，所以它可以是number或undefined。

键入

Number.isInteger仅接受类型为number的参数。因此TypeScript抱怨，因为maxORhealth也可能是数字。

要解决此问题，您可以执行以下两项操作之一。您可以像这样为undefined引入其他支票：

if (maxORhealth !== undefined && Number.isInteger(maxORhealth) && maxORstrength === undefined && mana === undefined) {
//  ^^^^^^^^^^^^^^^^^^^^^^^^^

Playground

或者，考虑到Number.isInteger(undefined)被正确处理并仅返回false，您还可以说服TypeScript仍然可以。为此，您可以使用非空断言后缀!运算符：

Number.isInteger(maxORhealth!)
//                          ^

此运算符告诉TypeScript maxORhealth不是undefined也不是null。

Playground

无法在构造函数定义中将类型“ undefined”分配给类型“ number”

1 个答案: