javascript - Should data functions be properties of a data array? -

i have dataset , functions manipulate data. store data , functions in logical structure readable , easy use without violating practices.

i see 2 options:

1. define data array , add manipulation functions array, possible because array kind of object.

example:

var dataset = [1, 2, 3, 4];  var dataset.add = function (newdata) {     if (newdata === baddata) {         console.log('bad data!');         return;     }     dataset.push(newdata); }; 

pros: cleaner, more readable, easier use

cons: modifying array object, means not behave expected, should not try copy object example, or document fact doing causes lose it's functions.

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2. define new object , define data property of object along manipulation functions.

example:

var dataset = {     data: [1, 2, 3, 4],      add: function (newdata) {         if (newdata === baddata) {            console.log('bad data!');            return;         }         data.push(newdata);     } }; 

pros: object works expected, can duplicated easily, , packages data , functions neatly.

cons: data cannot referenced canonical representation of object calling 'dataset'. data manipulation become tedious write in cases, due need call dataset.data instead of calling dataset.

which of these 2 options best , why? examples of these options in use today?

feel free offer better options well.

edit:

option 2a: (use prototype if have more 1 dataset)

option 3: don't attach data functions @ all. instead create separate array data outside of functions object , put data functions own object.

thanks!

in opinion second option better, cause said, modifying native object bad practice.

actually there third option, can create class, native data structure , expose method on it.

in way, able create multiple instances of same class.

class dataset {    constructor(data) {       this.data = data;    }     add(newdata) {       if (newdata === baddata) {          console.log('bad data!');          return;       }       data.push(newdata);     } } 

same implementation es5

var dataset = (function () {    function dataset(data) {        this.data = data;    }    dataset.prototype.add = function (newdata) {        if (newdata === baddata) {            console.log('bad data!');            return;        }        data.push(newdata);    };    return dataset; }()); 

wiki