How to set default module params in Javascript

Question

so i'm trying my hands on writing my very first library module using pure javascript except that i just hit a snag and need a little bit of help.

I'm using Revealing module pattern because of its neatness. In my module i have my default params in an object like this.

var defaults = {
   name : 'John Doe',
   age : 'Unspecified,
   height : '5feet'
};

And this works splendid, but i have an init function where a user can pass an object with these keys. e.g

Module.init({

     name : 'james',
     age : 12
});

Now in my code, i try to write a function that returns the values of each of these keys comparing the default values and the initialized one. If the key/value exists initialized, it should return it else use default. I know what i want, but don't know how to check the objects keys just yet.

function getValues (defaultObject, initObject){

   //scans the keys and returns the values

}

So in code i can do stuff like

var options = getValues(defaultObject, initObject);
var name = options.name;

This means that name will either be james if specified or john doe if not. Also for height since i didn't set a value, i get the default too

Thanks in advance guys.

Elhebert · Accepted Answer · 2017-01-15 18:23:30Z

0

What you need to do to compare both objects keys, and if the new object has a key, then replace the value in the old one. Here's an example:

function getValues(defaultObject, initObject) {
  for (var key in initObject) {
    if (initObject.hasOwnProperty(key)) {
      defaultObject[key] = initObject[key];
    }
  }

  return defaults;
}

I hope this help you.

answered Jan 15, 2017 at 18:23

Elhebert

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1 Comment

Elhebert Over a year ago

I'm glad I could help. Don't forget to accept the answer (for futur references)

Vitaliy Markitanov · Accepted Answer · 2018-08-29 17:14:47Z

0

See my answer in another thread how to better define function optional default params : https://stackoverflow.com/a/52082835/1422407

It may help you to redefine function signature, and as result less useless logic in function itself.

answered Aug 29, 2018 at 17:14

Vitaliy Markitanov

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