optimization of some javascript code

Question

the follwoing code

$.concat||$.extend({concat:function(b,c){var a=[];for(x in arguments)a=a.concat(arguments[x]);return a}}); 

$(document).ready(function(){

    //document ready

    var solobroadcast_template =$("#hidden_solobroadcast").html()
    var b = new Array();   
    b.push([{"indexname": "green", "url":"#Green"}])
    b.push([{"indexname": "red", "url":"#red"}])    
   //....... more elements come here 

   //how can we know b[] while the array b contain unknown keys
   var bindexes = $.concat(b[0],b[1]);   



    var convertedvars = {
        name: "sam",
        indexes: function (){return bindexes}

    }


    var output = Mustache.render(solobroadcast_template, convertedvars);
    document.getElementById("content").innerHTML = output;
});

as it runs on http://jsfiddle.net/mshannaq/ZqqMe/6/

as you can see the variable bindexes = $.concat(b[0],b[1]); and in this case its static for b[0] and b[1] but what shloud we do if we want to to cocat all the b array size . imagin that b array size may be 1000 element and its dynamic.

You could easily go through 1000 dynamic elements in nano seconds with a for loop. I don't think you need to optimize. The general rule is not to optimize until you have witnessed slowdowns. — Damien Black
– Damien Black, Commented Jan 5, 2014 at 2:26
if the b array have dynamic elements let says 1000 element how we will run the concat function — Mohammed Shannaq
– Mohammed Shannaq, Commented Jan 5, 2014 at 2:26
@DamienBlack "The general rule is not to optimize until you have witnessed slowdowns." Says who? How will you ever learn to optimize (or write secure code) unless you think about optimization (and security) with each and every line of code you write? — Joseph Myers
– Joseph Myers, Commented Jan 5, 2014 at 2:32
I don't understand why you're creating b[] as an array of arrays. As you have it, you're pushing an array of one object onto each element. Why not just push the object, then no concatenation will be required. — user1864610
– user1864610, Commented Jan 5, 2014 at 2:37

Dennis · Accepted Answer · 2014-01-05 02:54:01Z

1

Just add objects to the array instead adding the array:

b.push({"indexname": "green", "url":"#Green"})
b.push({"indexname": "red", "url":"#red"})

var convertedvars = {
    name: "sam",
    indexes: function (){return b;}
}

Then you already have an array of what you need, instead of concatenating all your smaller arrays.

Demo: http://jsfiddle.net/ZqqMe/11/

answered Jan 5, 2014 at 2:54

Dennis

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Community · Accepted Answer · 2017-05-23 11:56:47Z

0

in this case to fix this we use

 var bindexes = [];
 bindexes = bindexes.concat.apply(bindexes, b);

insted of using

var bindexes = $.concat(b[0],b[1]);

and now what ever how much b array elements they will be mereged

http://jsfiddle.net/mshannaq/ZqqMe/8/

as says on Merge/flatten an array of arrays in JavaScript?

edited May 23, 2017 at 11:56

CommunityBot

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answered Jan 5, 2014 at 2:53

Mohammed Shannaq

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