Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Methods that inherit via the prototype chain can be changed universally for all instances, for example:</p> <pre><code>function Class () {} Class.prototype.calc = function (a, b) { return a + b; } // Create 2 instances: var ins1 = new Class(), ins2 = new Class(); // Test the calc method: console.log(ins1.calc(1,1), ins2.calc(1,1)); // -&gt; 2, 2 // Change the prototype method Class.prototype.calc = function () { var args = Array.prototype.slice.apply(arguments), res = 0, c; while (c = args.shift()) res += c; return res; } // Test the calc method: console.log(ins1.calc(1,1,1), ins2.calc(1,1,1)); // -&gt; 3, 3 </code></pre> <p>Notice how changing the method applied to both instances? This is because <code>ins1</code> and <code>ins2</code> share the same <code>calc()</code> function. In order to do this with public methods created during construction, you'd have to assign the new method to each instance that has been created, which is an awkward task. This is because <code>ins1</code> and <code>ins2</code> would have their own, individually created <code>calc()</code> functions. </p> <p>Another side effect of creating methods inside the constructor is poorer performance. Each method has to be created every time the constructor function runs. Methods on the prototype chain are created once and then "inherited" by each instance. On the flip side of the coin, public methods have access to "private" variables, which isn't possible with inherited methods.</p> <p>As for your <code>function Class() {}</code> vs <code>var Class = function () {}</code> question, the former is "hoisted" to the top of the current scope before execution. For the latter, the variable declaration is hoisted, but not the assignment. For example:</p> <pre><code>// Error, fn is called before the function is assigned! fn(); var fn = function () { alert("test!"); } // Works as expected: the fn2 declaration is hoisted above the call fn2(); function fn2() { alert("test!"); } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POAdvantages of using prototype, vs defining methods straight in the constructor?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USAndy E
    1. USAndy E
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. POAdvantages of using prototype, vs defining methods straight in the constructor?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COAah, that makes things so much clearer :) I didn't realize the efficiency difference - that's very useful to know. Same for the hoisting effect - tricky, indeed. Thanks for such a great answer, I learned a lot from it!
      singulars
      1. PO
      1. USLeo
    2. COYou forgot to mention that it's harder to use Super.call.someFunction() when overriding in inheritance: http://stackoverflow.com/a/16063711/1641941
      singulars
      1. PO
      1. USHMR
 

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