CODEWITHSUNDEEP
javascriptjqueryarrays
pkExec
pkExec

Reputation: 2076

Most efficient way to filter through Javascript array of objects without standard keys

Let's say I have this (admittedly bad) structure:

var items = [
  {SomeString: [value1,value2...]},
  {AnotherString: [valueX,valueY...]},
  {YetAnotherString: [valueA,valueB...]}
];

I want to obtain the array assigned to "AnotherString".

One way (via jQuery) I am using:

$.each(items,function(x,item){
    $.each(item,function(key,values){
        if(key=="AnotherString"){
            //...do something
        }
    }
});

Obviously this is terribly inefficient, as it loops through needless items. One way would be to refactor it in a "while(!found)" loop.

My question: what's the most efficient way to filter through such an array?

Edit: forgot to clarify that I do not know in advance the key strings. This is used in an external loop where the key strings I am looking for are passed down.

Upvotes: 0

Views: 248

Answers (2)

georg
georg

Reputation: 215019

If you know that this structure is bad, why do you stick to it? Just use a normal object:

var obj = {
  SomeString: [value1,value2...],
  AnotherString: [valueX,valueY...],
  YetAnotherString: [valueA,valueB...]
};

If this is not possible for some reason, convert it dynamically:

obj = {};
items.forEach(function(item) {
    var key = Object.keys(item)[0];
    obj[key] = item[key];
});

This returns an object like the above. Once you have this, just do obj[someKey] when needed. No loops.

(This assumes, of course, that all keys are different).

Upvotes: 2

Niet the Dark Absol
Niet the Dark Absol

Reputation: 324760

Sometimes, stripping away jQuery and using Vanilla JS is the route to the most efficient solution.

items.some(function(item) {
    if( item.hasOwnProperty("AnotherString")) {
        // do something with item["AnotherString"]
        return true;
    }
    return false;
});

Documentation on the some function - Polyfill provided

Upvotes: 3

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