The attribute 'getTime' is not found in the data type 'number | Date'

Question

The attribute 'getTime' is not found in the data type 'number | Date'

class SW {
    private startTime: number | Date
    private endTime: number | Date

    constructor() {
        this.startTime = 0,
        this.endTime = 0
    }
    start() {
        this.startTime = new Date();    
    }
    stop() {
        this.endTime = new Date();   
    }

    getDuration() {
        const seconds = (this.endTime.getTime() - this.startTime.getTime()) / 1000;
    }
}

I'm encountering an issue with the error message:

Property 'getTime' does not exist on type 'number | Date'.

Attempting a solution as suggested in this Link, I have also tried to declare Date, but it didn't solve the problem.

interface Date {
    getTime(): number
}

If you have any ideas, they would be greatly appreciated.

javascript typescript oop

Answer 1

Answer №1

The variable in question is deemed as number | Date, indicating that it could be either data type. Initially, in your constructor, it is set as a number. However, upon calling start, it transitions from being a number to a Date. This transition creates ambiguity for TypeScript in the function getDuration where it cannot definitively determine its type (number or Date).

Upon reviewing your code, a suggestion could be to consistently use number by utilizing Date.now() instead of new Date() and omitting the usage of getTime:

class SW {
    private startTime: number;
    private endTime: number;

    constructor() {
        this.startTime = 0,
        this.endTime = 0
    }
    start() {
        this.startTime = Date.now();    
    }
    stop() {
        this.endTime = Date.now();   
    }

    getDuration() {
        const seconds = (this.endTime - this.startTime) / 1000;
    }
}

Additonally, you could consider implementing logic in getDuration to either raise an error or return NaN if this.endTime or this.startTime is set to 0.

Answer 2

The variable in question is deemed as number | Date, indicating that it could be either data type. Initially, in your constructor, it is set as a number. However, upon calling start, it transitions from being a number to a Date. This transition creates ambiguity for TypeScript in the function getDuration where it cannot definitively determine its type (number or Date).

Upon reviewing your code, a suggestion could be to consistently use number by utilizing Date.now() instead of new Date() and omitting the usage of getTime:

class SW {
    private startTime: number;
    private endTime: number;

    constructor() {
        this.startTime = 0,
        this.endTime = 0
    }
    start() {
        this.startTime = Date.now();    
    }
    stop() {
        this.endTime = Date.now();   
    }

    getDuration() {
        const seconds = (this.endTime - this.startTime) / 1000;
    }
}

Additonally, you could consider implementing logic in getDuration to either raise an error or return NaN if this.endTime or this.startTime is set to 0.

Answer 3

Answer №2

Simplify it

class Timer {
  private start: number;
  private end: number;
 
  begin() {
    this.start = new Date().getTime(); 
  }
  finish() {
    this.end = new Date().getTime();
  }

  getElapsedTime() {
    return (this.end - this.start) / 1000;
  }
}

Answer 4

Simplify it

class Timer {
  private start: number;
  private end: number;
 
  begin() {
    this.start = new Date().getTime(); 
  }
  finish() {
    this.end = new Date().getTime();
  }

  getElapsedTime() {
    return (this.end - this.start) / 1000;
  }
}

The attribute 'getTime' is not found in the data type 'number | Date'

Answer №1

Answer №2

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