Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>The correct answer is: you can't do that, as <a href="https://stackoverflow.com/questions/5525795/does-javascript-guarantee-object-property-order">objects are unordered as per ECMAScript's spec</a>.</p> <p>I'd recommend that you use an ordered structure, like an array, for the purpose of the problem:</p> <pre><code>var db = [ {key: 'a', value: 1}, {key: 'b', value: 2}, {key: 'c', value: 3} ]; </code></pre> <p>Then the <code>next</code> function can be something like:</p> <pre><code>var next = function(db, key) { for (var i = 0; i &lt; db.length; i++) { if (db[i].key === key) { return db[i + 1] &amp;&amp; db[i + 1].value; } } }; </code></pre> <p>In case <code>key</code> does not exist on <code>db</code> or it was the last one, <code>next</code> returns <code>undefined</code>. if you're never going to ask for the next of the last item, you can simplify that function by removing the ternary <code>&amp;&amp;</code> operator and returning <code>db[i + 1].value</code> directly.</p> <p>You can also use some of Underscore.js utility methods to make <code>next</code> simpler:</p> <pre><code>var next = function(db, key) { var i = _.pluck(db, 'key').indexOf(key); return i !== -1 &amp;&amp; db[i + 1] &amp;&amp; db[i + 1].value; }; </code></pre> <p>(in this case <code>next</code> could return <code>false</code> sometimes... but it's still a falsy value :))</p> <hr> <p>Now, a more pragmatic answer could be that, as most browsers will respect the order in which an object was initialized when iterating it, you can just iterate it with a <code>for in</code> loop as the other answers suggest. I'd recommend using <a href="https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/keys" rel="nofollow noreferrer"><code>Object.keys</code></a> to simplify the job of iterating over the array:</p> <pre><code>// Assuming that db is an object as defined in the question. var next = function(db, key) { var keys = Object.keys(db) , i = keys.indexOf(key); return i !== -1 &amp;&amp; keys[i + 1] &amp;&amp; db[keys[i + 1]]; }; </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POGet next key-value pair in an object
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USepidemian
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POGet next key-value pair in an object
      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. VTDownMod
    1. CO@just2n Fair enough, those are all valid points. About the performance overhead, i think we don't have much information about the size of the input or whether this is a performance-critical operation. Without knowing much about how this is going to be used, or even how the input is constructed, i find it difficult to claim that the performance overhead of this solution versus others would be noticeable. About the order of Object.keys, yes, it's undefined, that's why i mentioned it in the "pragmatic" solution, which is not very correct. [...]
      singulars
      1. PO
      1. USepidemian
    2. CO[...] I appreciate the criticism, but i think you're being overly negative in your comment. There is no indication that the answer was accepted based solely on reputation; maybe the OP thought the code was simpler to understand/maintain or they simply preferred the approach of storing everything into a plain array.
      singulars
      1. PO
      1. USepidemian
 

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