I am writing some code in Node.js that jumped out at me as being better structured using the strategy pattern. Coming from .Net I would create the interface the rest were based on and move from there, in JavaScript this is not so clear cut.

I understand as a prototypical language JavaScript does not have the notion of interface inheritance, so I am not sure what I have done is a smell or not, as I cant seem to find references, apart from one blog post which tries to infer an interface by using a base abstract class which forces the inheriting classes to implement the function (as it throws).

My base class

QueryStrategy = function () {

};

QueryStrategy.prototype.create = function(){
throw new Error("Not Implemented");
}

module.exports = QueryStrategy;

Implementation 1

var util = require('util');
var QueryStrategy = require('./queryStrategy');

SelectQueryStrategy = function (query) {
    this.parameters = query.parameters || [];
    this.entity = query.entity || '';
};

util.inherits(SelectQueryStrategy, QueryStrategy);

SelectQueryStrategy.prototype.create = function () {
    var self = this,
        params = self.parameters,
        paramList = self.parameters.length >= 1 ? '' : '*';

    for (var i = 0; i < params.length; i++) {
        var suffix = i === (params.length - 1) ? '' : ', ';
        paramList = paramList + params[i].key + suffix;
    }

    return util.format("SELECT %s FROM %s", paramList, self.entity);
};

module.exports = SelectQueryStrategy;

Currently the base does not have any shared functions, or properties. Shared functions will come, properties, because of the prototypical chain search i didn't see the point of adding the "shared" properties as they are overwritten by the instances created (please if this is wrong, let me know).

Is this an acceptable approach or should I disregard inheritance in this insta

javascript oop node.js
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