Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I'm assuming that by <em>empty</em> you mean "has no properties of its own".</p> <pre><code>// Speed up calls to hasOwnProperty var hasOwnProperty = Object.prototype.hasOwnProperty; function isEmpty(obj) { // null and undefined are "empty" if (obj == null) return true; // Assume if it has a length property with a non-zero value // that that property is correct. if (obj.length &gt; 0) return false; if (obj.length === 0) return true; // If it isn't an object at this point // it is empty, but it can't be anything *but* empty // Is it empty? Depends on your application. if (typeof obj !== "object") return true; // Otherwise, does it have any properties of its own? // Note that this doesn't handle // toString and valueOf enumeration bugs in IE &lt; 9 for (var key in obj) { if (hasOwnProperty.call(obj, key)) return false; } return true; } </code></pre> <p>Examples:</p> <pre><code>isEmpty(""), // true isEmpty(33), // true (arguably could be a TypeError) isEmpty([]), // true isEmpty({}), // true isEmpty({length: 0, custom_property: []}), // true isEmpty("Hello"), // false isEmpty([1,2,3]), // false isEmpty({test: 1}), // false isEmpty({length: 3, custom_property: [1,2,3]}) // false </code></pre> <p>If you only need to handle <a href="http://caniuse.com/#search=use-strict">ECMAScript5 browsers</a>, you can use <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames"><code>Object.getOwnPropertyNames</code></a> instead of the <a href="https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Object/hasOwnProperty"><code>hasOwnProperty</code></a> loop:</p> <pre><code>if (Object.getOwnPropertyNames(obj).length &gt; 0) return false; </code></pre> <p>This will ensure that even if the object only has non-enumerable properties <code>isEmpty</code> will still give you the correct results.</p>
    singulars
    1. This table or related slice is empty.
    1. POIs object empty?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USSean Vieira
    1. USSean Vieira
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POIs object empty?
      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. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COYes, but you have to declare it as a local variable using `var`. Otherwise, it is an assignment which makes `hasOwnProperty` an implicit global variable. Just place `var` in front of your assignment and it will be OK.
      singulars
      1. PO
      1. USŠime Vidas
    2. CO@Šime Vidas *Smacks head* -- thanks for the catch!
      singulars
      1. PO
      1. USSean Vieira
    3. CO@SeanVieira is_empty({length: 0, custom_property: []}) returns false. I'm not sure how you intended the code to work, but I would expect it if you add: if (obj.length === 0) return true; after if (obj.length && obj.length > 0) return false; it would be correct
      singulars
      1. PO
      1. USpgreen2
 

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