Issue
The parameter value maxORhealth prompts the following error; in VS Code:
Type 'undefined' is not assignable to type 'number'.ts(2345)
... and unsure how to navigate around this error.
Class Definition
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;
}
}
}
Desired Affect
I would like to have three constructors for this class, as follows:
constructor()
constructor(maxORhealth: number)
constructor(maxORhealth: number, maxORstrength: number)
constructor(maxORhealth: number, maxORstrength: number, mana: number, stamina: number, intelect: number, tune: number)
... with (hopefully) a practical (none overly JS fancy) solution.
The error originates from this statement:
Number.isInteger(maxORhealth)
maxORhealth is of type number | undefined. Because it's an optional argument to the constructor, it can be either a number or undefined.
Number.isInteger is typed to only accept a parameter of type number. Therefore TypeScript complains because maxORhealth could also be a number.
To fix this you can do one of two things. You can introduce an additional check for undefined like this:
if (maxORhealth !== undefined && Number.isInteger(maxORhealth) && maxORstrength === undefined && mana === undefined) {
// ^^^^^^^^^^^^^^^^^^^^^^^^^
Alternatively, considering Number.isInteger(undefined) is handled properly and just returns false, you could also convince TypeScript that it's okay anyway. To do that you can use the non-null assertion postfix ! operator:
Number.isInteger(maxORhealth!)
// ^
This operator tells TypeScript that maxORhealth is not undefined and not null.