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Groups > comp.lang.javascript > #34596

Re: Get the object structure correct.

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Michael Haufe (TNO) wrote:

> Jonas Thörnvall wrote:
>> var People = [
>>     {Name: "Name", Surname: "Surname"},
>>     {Name:"AAA", Surname:"ZZZ"},
>>     {Name: "Name", Surname: "AAA"}
>> ];
>> I guess people is an array holding three indexes above?
>> The properties of people is Name and Surname
> 
> JavaScript developers have a tendency to "golf" [1] their code just like
> Perl programmers. Which can make things unnecessarily terse.

But often also less error-prone.  YMMV.
 
> I would have wrote the example like this:
> 
> </script>
> class Person {
>     constructor(name, surName) {
>         this.name = name;
>         this.surName = surName
>     }
> }
> 
> var people = [
>     new Person(Brendan", "Eich"),
>     new Person("Alan","Kay"),
>     new Person("Robert", "Carlyle")
> ]

Names starting with a capital letter should be reserved for constructors, 
classes and constants  That is, “People”, “Name”, and “Surname” should all 
be lowercase here.

Using the same pattern as you used for “tracks”, one can set up the data and 
have the custom instances without repeating oneself (ES 2015+):

  people = people.map((obj) => new Person(obj.name, obj.surname));

or, more backwards-compatible (ES Ed. 5+):

  people = people.map(function (obj) {
    return new Person(obj.name, obj.surname);
  });

Or, most backwards-compatible (all):

  for (var i = people.length; i--;)
  {
    var obj = people[i];
    people[i] = new Person(obj.name, obj.surname);
  };

If the class/type has a default constructor (and this is one example that 
show that it is a good idea to have one), and provides means to set 
individual properties, then this can be even simpler.  For example:

  people = people.map((obj) => {
    var person = new Person();
    Object.assign(person, obj);
  });

It is also a good idea to have a constructor that in addition to positional 
arguments accepts an initializer object as first and only argument.

  people = people.map((obj) => new Person(obj));

Such a constructor is particularly useful with JSON.parse(json, reviver), 
and in general it is a good idea if a constructor can be called as a 
function for type conversion (like type casting).  But apparently this is 
not possible with ECMAScript classes:

  class Person
  {
    constructor (...args)
    {
      if (!(this instanceof Person)) return new Person(...args);

      /* initialize */
    }
  }

  /* TypeError: Class constructor Person cannot be invoked without 'new' */
  Person()

This works:

  function Person (...args)
  {
    /* 
     * For backwards compatibility JSX:object.js introduces 
     * Function.prototype.construct(), and I am also thinking about
     * adding Function.prototype.toFactory() for DRY.
     */
    if (!(this instanceof Person)) return new Person(...args);

    /* initialize */
  }

  /* > Person {} */
  Person()

BTW, one should have read <http://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/>.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | <http://PointedEars.de/es-matrix>
<https://github.com/PointedEars> | <http://PointedEars.de/wsvn/>
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Thread

Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 02:50 -0800
  Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 03:03 -0800
  Re: Get the object structure correct. "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-01-18 14:39 -0800
    Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 16:38 -0800
      Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 16:56 -0800
        Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 17:19 -0800
          Re: Get the object structure correct. "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-01-18 17:33 -0800
            Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 19:54 -0800
            Re: Get the object structure correct. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-01-19 04:55 +0100
              Re: Get the object structure correct. "Mark-" <nospam@mapson.xyz> - 2018-01-19 04:03 +0000
              Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 20:06 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 20:30 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 20:49 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-19 00:12 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-19 02:01 -0800
                Re: Get the object structure correct. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-01-25 07:49 +0100
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-30 01:06 -0800
                Re: Get the object structure correct. Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-01-30 11:01 +0100
                Re: Get the object structure correct. "Mark-" <nospam@mapson.xyz> - 2018-01-30 13:37 +0000
                Re: Get the object structure correct. John G Harris <niam@jghnorth.org.uk.invalid> - 2018-01-30 19:14 +0000
      Re: Get the object structure correct. "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-01-18 17:24 -0800
        Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 17:41 -0800
          Re: Get the object structure correct. "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-01-18 17:47 -0800
            Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 18:29 -0800
              Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 18:46 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 18:54 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-18 19:00 -0800
        Re: Get the object structure correct. John G Harris <niam@jghnorth.org.uk.invalid> - 2018-01-19 11:20 +0000
          Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-19 11:48 -0800
            Re: Get the object structure correct. John G Harris <niam@jghnorth.org.uk.invalid> - 2018-01-19 20:03 +0000
              Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-19 12:18 -0800
              Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-19 12:48 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-19 13:02 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-20 18:07 -0800
                Re: Get the object structure correct. Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-01-21 00:55 -0800

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