Adding for loop results to an array and displaying sum of added elements after the last loop

Question

I have to get some records based on weekly basis for the last weeks, and have to add values from records of one week to an array. So, I declared 6 arrays to store 6 weeks records. My code is:

var w_0 = [];var w_1 = [];var w_2 = [];var w_3 = [];var w_4 = [];var w_5 = [];
var myTotal = 0;
var arr_name = "";

for(var j=0;j<=5;j++)
{

    var start_date="";
    var end_date="";

    //code to fetch the records added between start_date,end_date
    //there may be more that one record

    var count = getRecordCount(); //My function
    //following loop is to fetch value from a record
    for(var i=0;i<count;i++)    
    {
        var val1 = getRecordByIndex(i).getValue("rem_val"); //getRecordByIndex() and getValue() are our pre-defined functions. 

        //here I want to push the values into the array w_0

        arr_name = "w_"+j;
        [arr_name].push(val1); //this is not working
        alert([arr_name]); //showing 'w_0'

    } 

    //and here I want to sum all the array elements when i reaches its maximum
    for(var a=0;a<[arr_name].length; a++){
        myTotal += parseInt([arr_name][a]);  
    }
    alert("Total value of week"+j+"="+parseInt(myTotal)); 
}

How can I add values of inner loop to the array based on outer loop?

You can't access variables by name. Why don't you just use a 2-dimensional array? — Barmar
– Barmar, Commented Jan 23, 2014 at 12:12
[arr_name] isn't a reference to the array whose name is in arr_name. It's an array containing the string in arr_name. — Barmar
– Barmar, Commented Jan 23, 2014 at 12:15
["string"] creates an array which contains "string". If we change your code to instead use var a = ["string"]; a.push("val"); we'd end up with ["string", "val"]. This is what your code currently does; it creates an array containing a string (which is equal to the name of whichever of your array variables) which isn't assigned to any variable itself, then pushes val1 into it. — James Donnelly
– James Donnelly, Commented Jan 23, 2014 at 12:16
will this work then. var all_arrays = {w_0:[],w_1:[],w_2:[],w_3:[],w_4:[],w_5:[]}; arr_name = "w_"+j;all_arrays[arr_name].push(val1); — M.K
– M.K, Commented Jan 23, 2014 at 12:22

Barmar · Accepted Answer · 2014-01-23 12:19:10Z

1

Any time you find yourself creating variables with sequentially numbered names, you should probably be using an array instead.

var w = [[], [], [], [], []];

Then, wherever you tried to use [arr_name] to refer to a particular w_j variable, you should use w[j].

for(var j=0;j<=w.length;j++)
{

    var cur_w = w[j];
    var start_date="";
    var end_date="";

    //code to fetch the records added between start_date,end_date
    //there may be more that one record

    var count = getRecordCount(); //My function
    //following loop is to fetch value from a record
    for(var i=0;i<count;i++)    
    {
        var val1 = getRecordByIndex(i).getValue("rem_val"); //getRecordByIndex() and getValue() are our pre-defined functions. 

        cur_w.push(val1);
        alert(cur_w);

    } 

    //and here I want to sum all the array elements when i reaches its maximum
    for(var a=0;a<cur_w.length; a++){
        myTotal += parseInt(cur_w[a]);  
    }
    alert("Total value of week"+j+"="+parseInt(myTotal)); 
}

answered Jan 23, 2014 at 12:19

Barmar

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1 Comment

Barmar Over a year ago

You need to set myTotal to 0 before the totaling loop.

Goran.it · Accepted Answer · 2014-01-23 12:15:59Z

0

If you want to dynamically manipulate global variables you can use window prefix:

arr_name = "w_"+j;
window[arr_name].push(val1); // This should work

answered Jan 23, 2014 at 12:15

Goran.it

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2 Comments

Barmar Over a year ago

You can only do that with global variables, not local variables.

Goran.it Over a year ago

For local you can create object that contains all of the arrays and use that instead of the window prefix.. something like var store = {}; store.w_1 = []; etc..

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