Adding meta data to a primitive in javascript

Question

Background

We have much of our data formatted like

var X = {value:'some val',error:'maybe an error',valid:true}

as a result we find ourselves calling X.value ALL the time.
We don't use the .error or .valid nearly as much, but we do use it.

What I want

To quit calling .value everywhere, but to still have access to meta data on a per data point level.

The Question

Is there one of

A) A way to put meta data on a primitive? attaching .error to an int for example? Is it possible for bools or strings?

B) A way to make a class that can be treated as a primitive, providing a specific data member when I do? IE X.value = 5, X+3 returns 8.

C) A better design for our data? Did we just lay this out wrong somehow?

Julio Betta · Accepted Answer · 2017-05-05 14:45:28Z

1

You can set the method toString() to your object and return value.

var X = {
  value: 1,
  error:'maybe an error',
  valid:true,
  
  toString: function() {
    return this.value;
  }
}

X.value = 5;
console.log(X+3);

answered May 5, 2017 at 14:45

Julio Betta

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Comments

amiramw · Accepted Answer · 2017-05-05 15:27:20Z

0

You can represent you data as a function object that also has properties:

var X = () => 1;
X.value = 1;
X.error = 'maybe an error';
X.valid = true,

console.log(X()); // 1
console.log(X.valid); // true

For better design you can encapsulate the creation of the data object in another function.

edited May 5, 2017 at 15:27

answered May 5, 2017 at 15:00

amiramw

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