Javascript Question posted in
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Javascript – How to do a class method that is not a function?

class Library {
    constructor(a){
    this.total = a;
    }
            
        add(...a){
            for (const arg of a) {
                  this.total += arg;
            }
            return this;
        }
        
        subtract(...b){
            for (const args of b) {
              this.total -= b;
            }
            return this;
            }
            
   
        result() {
            console.log(this.total);
            return this.total
            }
            
       
            


}

    $ = new Library(10); // inititliaize the base as 10

// var x = $.add(3,5).add(5,10).subtract(10).result;    
// x should be 10+3+5+5+10-10 or basically 23
// var y = $.add(3,5).add(5,10).subtract(10,3,5).result to return 15

The problem requires the exact line.

var x = $.add(3,5).add(5,10).subtract(10).result;

The problem requires to chain a method "result" that is not a function I tried

  result = function(){
    return this.total;
  };

Is there a way to return a value in a class without using a function?

Tags:

3

Answers


  1. 0

    Option 1:

    You can achieve the expected line format using a getter:

    class Library {
  constructor(a){
    this.total = a;
  }
            
  add(...a) {
    for (const arg of a) {
      this.total += arg;
    }
    return this;
  }
        
  subtract(...b){
    for (const arg of b) {
      this.total -= arg;
    }
    return this;
  }
 
  get result() {
    console.log(this.total);
    return this.total
  }
}

const $ = new Library(10);
console.log($.add(3,5).add(5,10).subtract(10).result);

    Technically, it’s a function call, but you omit the parenthesis.

    Option 2:

    You can store the result after each calculation:

    class Library {
  constructor(a){
    this.total = a;
    this.result = this.total;
  }
            
  add(...a) {
    for (const arg of a) {
      this.total += arg;
    }
    this.result = this.total;
    return this;
  }
        
  subtract(...b){
    for (const arg of b) {
      this.total -= arg;
    }
    this.result = this.total;
    return this;
  }
}

const $ = new Library(10);
console.log($.add(3,5).add(5,10).subtract(10).result);
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  2. 0

    In python there is the @property decorator which is really helpul to avoid to call a function and just return the value of the property.

    in that case in JS you need to use the get which binds an object property to a function that will be called when that property is looked up.

    get result() {
  return this.total
}
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  3. 0

    I’m not sure why you are trying to complicate this, when the obvious answer is to make use of a public class field named result.

    class Library {
    result;
    
    constructor(a) {
        this.result = a;
    }
         
    add(...a){
        for (const arg of a) {
          this.result += arg;
        }
        return this;
    }  
    subtract(...b){
        for (const arg of b) {
           this.result -= b;
        }
        return this;
    }
}

$ = new Library(0);
var x = $.add(3,5).add(5,10).subtract(10).result;
console.log(x);
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