Yoran Cobben Yoran Cobben - 1 month ago 30
TypeScript Question

Typescript, toFixed. Type 'string' is not assignable to type 'number'

distanceX = ((this.frontclickedX - originX) / originX).toFixed(2);
distanceY = (-(this.frontclickedY - originY) / originY).toFixed(2);
let distanceZ: number = (-(this.frontclickedY - originY) / originY).toFixed(2);


my browser throws an error when I calculated distanceZ:

Type 'string' is not assignable to type 'number'.


the first two lines work perfectly, but the third doesn't really work.
As you can see it is even exact the same calculation as distanceY. I tried to parseFloat() it first. But then it starts to complain that I can only parse a string to a float, and that I didn't provide one.

I'm quite confused at the moment, so some help or a solution would be much appreciated!

Thanks in advance!

Edit: I tried to simplify my code.
Made the distances private and added setters and getters.

private _distanceX: number;
private _distanceY: number;
private _distanceZ: number;

get distanceZ(): number {
return this._distanceZ;
}
set distanceZ(value: number) {
this._distanceZ = value;
} ...
calculateBadgeDistance(): void{
this.distanceX = (5.001).toFixed(2);
this.distanceY = (5.001).toFixed(2);
this.distanceZ = (5.001).toFixed(2);
}


Now I got the error on all 3 lines.

Answer

The method toFixed() converts a number to a string. You have to parse the variables to numbers:

let distanceZ:number = parseFloat((-(this.frontclickedY - originY) / originY).toFixed(2));

Alternatively temporary store the string, and parse it later

let distanceZTxt:string = (-(this.frontclickedY - originY) / originY).toFixed(2);
let distanceZ:number = parseFloat(distanceZTxt);
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