Databases
StackOverflow2013
Postsdbo
POAdvantages & Disadvantages of Dependency-Injecting Non-Instantiable Objects
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POAdvantages & Disadvantages of Dependency-Injecting Non-Instantiable Objects
    primarykey
    data
    text
    <p>What, in your opinion, are the advantages and disadvantages of dependency-injecting non-instantiable objects in <strong>JavaScript</strong>?</p> <p>Some context you may want to explore are: </p> <ul> <li><strong>Unit-testing</strong> <ul> <li>Is it worth dep-injecting it? After all, you can overwrite the non-instantiable "static" dependency to a fake object for each test even without dep-injection.</li> </ul></li> <li><strong>Refactoring</strong> <ul> <li>Will it become more difficult to locate &amp; refactor the non-instantiable dependency?</li> </ul></li> <li><strong>Readability</strong> <ul> <li>Which implementation is easier to follow? Is the implicitness or explicitness important to you?</li> </ul></li> <li><strong>File-size</strong></li> </ul> <p><br/></p> <h2>Code</h2> <p>Non-instantiable object:</p> <pre><code>WindowFactory = { buildWindow: function() { return {}; } }; </code></pre> <p>Dependency-Injected:</p> <pre><code>(House = function(windowFactory) { this.windowFactory = windowFactory; }).prototype = { build: function() { var window = this.windowFactory.buildWindow(); } }; var house = new House(WindowFactory); </code></pre> <p>vs. The Non-Dependency-Injected variant:</p> <pre><code>(House = function() { }).prototype = { build: function() { var window = WindowFactory.buildWindow(); } }; var house = new House(); </code></pre> <p><br/></p> <h2>Context</h2> <p>My primary goal is to make the code above testable. I've gotten into a habit of externalizing instantiable dependencies (e.g <code>var window = new Window(); var house = new House(window);</code>). This helps when unit- testing instantiable objects (e.g. <code>House</code>), since instead of the real dependencies (<code>Window</code>) I can instantiate the object with a fake (<code>var fakeWindow = {}; var house = new House(fakeWindow);</code>), and not have to worry about redundantly testing the dependencies while testing my object. (This form of dependency-injection is also useful when testing objects that depend on some data being retrieved via XHR, DOM-events, sessionStorage, or cookie.) </p> <p>Now, when the dependency is an instantiable object itself, the benefits are clear to me; but when the dependency is a non- instantiable object (e.g. WindowFactory in the code above), I have second thoughts about the usefulness. </p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USYuriy Nemtsov
    1. USYuriy Nemtsov
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POAdvantages & Disadvantages of Dependency-Injecting Non-Instantiable Objects
      1. USKonerak
      1. VTFavorite
    2. VO
      singulars
      1. POAdvantages & Disadvantages of Dependency-Injecting Non-Instantiable Objects
      1. This table or related slice is empty.
      1. VTUpMod
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload