can you help me with a doubt?

I'm trying an approach more didatical in JS, creatind a POJO/POCO for a model class.

I have a Person object:

function person(name, age, gender) {
      this.name = name;
      this.age = age;
      this.gender = gender;
      return this;
}

Now I can create some data:

var personalities = new Array(new person("Alicia", 152, "F"), 
                              new person("Bartolomeu Simpson", 36, "M"),
                              new person("Ayrton Senna", 58, "M"),
                              new person("Jean J. Michel", 36, "M"),
                              new person("Jean J. Michel", 37, "M"));

Well, done it if I call sort method there is no action to order this data:

personalities.sort();

for(var i = 0; i < personalities.length; i++)
  console.log(personalities[i].name);

Output is:

Alicia
Bartolomeu Simpson
Ayrton Senna
Jean J. Michel
Jean J. Michel

I created a toString() method:

function person(name, age, gender) {
  this.name = name;
  this.age = age;
  this.gender = gender;

  this.toString = function() {
    return this.name + " " + 
           this.age + " years old" + 
           (this.gender == 'M' ? " man" : " woman");
  };

  return this;
}

Now the sort method is "ok", the output now is:

Alicia
Ayrton Senna
Bartolomeu Simpson
Jean J. Michel
Jean J. Michel

But I want do something different, order by name and age (oldest first). I implemented the method pareTo(obj):

function person(name, age, gender) {
  this.name = name;
  this.age = age;
  this.gender = gender;

  this.toString = function() {
    return this.name + " " + 
           this.age + " years old" + 
           (this.gender == 'M' ? " man" : " woman");
  };

  thispareTo = function(otherPerson) {
    var resultOfComparison = 0;

    if(this.name > otherPerson.name) {
      resultOfComparison = 1;
      return resultOfComparison;
    }
    else if(this.name < otherPerson.name) {
      resultOfComparison = -1;
      return resultOfComparison;
    }
    else if(this.age > otherPerson.age) {
      resultOfComparison = -1;
      return resultOfComparison;
    }
    else if(this.age < otherPerson.age) {
      resultOfComparison = 1;
      return resultOfComparison;
    }

    return resultOfComparison;
  };

  return this;
}

The method is ok, look it:

var jean1 = new person("Jean J. Michel", 36, "M");
var jean2 = new person("Jean J. Michel", 37, "M");

console.log(jean1pareTo(jean2)); //1
console.log(jean1pareTo(jean1)); //0
console.log(jean2pareTo(jean1)); //-1

Can I use this approach to sort my array? Something like this:

personalities.sort(personpareTo);

I really do not want to do it in a service class that use my model:

personalities.sort(function(personA, personB) {
                     var resultOfComparison = 0;

                     if(personA.name > personB.name) {
                       resultOfComparison = 1;
                       return resultOfComparison;
                     }
                     else if(personA.name < personB.name) {
                       resultOfComparison = -1;
                       return resultOfComparison;
                     }
                     else if(personA.age > personB.age) {
                       resultOfComparison = -1;
                       return resultOfComparison;
                     }
                     else if(personA.age < personB.age) {
                       resultOfComparison = 1;
                       return resultOfComparison;
                     }

                     return resultOfComparison;
                   });

I think that this is a model responsibility.

Thanks for all help.

can you help me with a doubt?

I'm trying an approach more didatical in JS, creatind a POJO/POCO for a model class.

I have a Person object:

function person(name, age, gender) {
      this.name = name;
      this.age = age;
      this.gender = gender;
      return this;
}

Now I can create some data:

var personalities = new Array(new person("Alicia", 152, "F"), 
                              new person("Bartolomeu Simpson", 36, "M"),
                              new person("Ayrton Senna", 58, "M"),
                              new person("Jean J. Michel", 36, "M"),
                              new person("Jean J. Michel", 37, "M"));

Well, done it if I call sort method there is no action to order this data:

personalities.sort();

for(var i = 0; i < personalities.length; i++)
  console.log(personalities[i].name);

Output is:

Alicia
Bartolomeu Simpson
Ayrton Senna
Jean J. Michel
Jean J. Michel

I created a toString() method:

function person(name, age, gender) {
  this.name = name;
  this.age = age;
  this.gender = gender;

  this.toString = function() {
    return this.name + " " + 
           this.age + " years old" + 
           (this.gender == 'M' ? " man" : " woman");
  };

  return this;
}

Now the sort method is "ok", the output now is:

Alicia
Ayrton Senna
Bartolomeu Simpson
Jean J. Michel
Jean J. Michel

But I want do something different, order by name and age (oldest first). I implemented the method pareTo(obj):

function person(name, age, gender) {
  this.name = name;
  this.age = age;
  this.gender = gender;

  this.toString = function() {
    return this.name + " " + 
           this.age + " years old" + 
           (this.gender == 'M' ? " man" : " woman");
  };

  this.pareTo = function(otherPerson) {
    var resultOfComparison = 0;

    if(this.name > otherPerson.name) {
      resultOfComparison = 1;
      return resultOfComparison;
    }
    else if(this.name < otherPerson.name) {
      resultOfComparison = -1;
      return resultOfComparison;
    }
    else if(this.age > otherPerson.age) {
      resultOfComparison = -1;
      return resultOfComparison;
    }
    else if(this.age < otherPerson.age) {
      resultOfComparison = 1;
      return resultOfComparison;
    }

    return resultOfComparison;
  };

  return this;
}

The method is ok, look it:

var jean1 = new person("Jean J. Michel", 36, "M");
var jean2 = new person("Jean J. Michel", 37, "M");

console.log(jean1.pareTo(jean2)); //1
console.log(jean1.pareTo(jean1)); //0
console.log(jean2.pareTo(jean1)); //-1

Can I use this approach to sort my array? Something like this:

personalities.sort(person.pareTo);

I really do not want to do it in a service class that use my model:

personalities.sort(function(personA, personB) {
                     var resultOfComparison = 0;

                     if(personA.name > personB.name) {
                       resultOfComparison = 1;
                       return resultOfComparison;
                     }
                     else if(personA.name < personB.name) {
                       resultOfComparison = -1;
                       return resultOfComparison;
                     }
                     else if(personA.age > personB.age) {
                       resultOfComparison = -1;
                       return resultOfComparison;
                     }
                     else if(personA.age < personB.age) {
                       resultOfComparison = 1;
                       return resultOfComparison;
                     }

                     return resultOfComparison;
                   });

I think that this is a model responsibility.

Thanks for all help.

• javascript
• node.js
• oop

• Why not pass .sort() a small function that just returns personA.pareTo(personB)? – Pointy Commented Apr 3, 2018 at 12:39
• How to do it? Can you show me the way? – Jean J. Michel Commented Apr 4, 2018 at 14:52
• personalities.sort((personA, personB) => personA.pareTo(personB)); – Pointy Commented Apr 4, 2018 at 14:53

2 Answers 2

Well, the parator function you pass to sort() needs to take two arguments, so it can't be an instance method. I'd suggest you define it as a "static" method:

function person(name, age, gender) {
    this.name = name;
    this.age = age;
    this.gender = gender;
}

person.pare = function(personA, personB) {
    if(personA.name > personB.name) return 1;
    if(personA.name < personB.name) return -1;
    return personB.age - personA.age;
}

And then you can call it when you sort:

personalities.sort(person.pare);

I hope I understood correctly what you were asking.

Really thanks for all responses. Máté gave me the path for a subject that I had not really knowlegment in JS.

My final class is:

function person(name, age, gender) {
    this.name = name;
    this.age = age;
    this.gender = gender;

    this.toString = function() {
      return this.name + " " + 
             this.age + " years old" + 
             (this.gender == 'M' ? " man" : " woman");
    };

    return this;
}

And my pareTo method now is static:

person.pareTo = function(personA, personB) {
                     var resultOfComparison = 0;

                     if(personA.name > personB.name) {
                       resultOfComparison = 1;
                       return resultOfComparison;
                     }
                     else if(personA.name < personB.name) {
                       resultOfComparison = -1;
                       return resultOfComparison;
                     }
                     else if(personA.age > personB.age) {
                       resultOfComparison = -1;
                       return resultOfComparison;
                     }
                     else if(personA.age < personB.age) {
                       resultOfComparison = 1;
                       return resultOfComparison;
                     }

                     return resultOfComparison;
                   };

All this code is in PersonModel.js.

Now at my service/DAO I can do this:

var personalities = new Array(new person("Bartolomeu Simpson", 36, "M"),
                              new person("Ayrton Senna", 58, "M"),
                              new person("Jean J. Michel", 36, "M"),
                              new person("Jean J. Michel", 37, "M"),
                              new person("Alicia", 152, "F"));

personalities.sort(person.pareTo);

And the result will be:

Alicia 152 years old woman
Ayrton Senna 58 years old man
Bartolomeu Simpson 36 years old man
Jean J. Michel 37 years old man
Jean J. Michel 36 years old man

Well done, closed case :)