Declare empty array in javascript

Question

update

My code that works. When page is loaded

    product= [[],[]];

then the code executed after ajax call:

$('#contextreload ul').each(function(i, ul) {
product.push([]);
});

$('#contextreload ul').each(function(i, ul) {
  allline=i; 
  $('#reloadajax'+i+' li').each(function(lk, li) {
  var lilk = $(li).html();  product[i][lk]=lilk;

  // your code goes here
 });

  // your code goes here
});

To use eval(); in ajax response for this, with some changes in php file? /endupdate

product[0]=[1,2,3,4];

product[1]=[a,b,x,z];

.

product[10]=[extra,extra,extra,extra];

When I load the page this is executed: product= [[],[],[],[],[],[],[],[],[],[]];

But if I declare this, when I call ajax I can ~~push~~ add data only to this array (10 rows) If I have 11 rows (product[10][0] and product[10][1]), the extra data will not be added. After ajax call I need the extra data : product= [[],[],[],[],[],[],[],[],[],[],**[11]**];

This function is because I want to put data in array after loading ajax data from php file.

$('#contextreload ul').each(function(i, ul) {
 <strike> var product = $(ul).html();  </strike>
    allline = i; 

    $('#reloadajax'+i+' li').each(function(lk, li) {
        var lilk = $(li).html();  
        product[i][lk]=lilk;
        alert(lilk+lk);
        // your code goes here
    });
    // your code goes here
});


}

Why pre-allocate/dimension? Create a basic empty array =[]; then .push to it in the loop as needed — Alex K.
– Alex K., Commented Mar 25, 2015 at 11:26
I change the data after ajax call. First time I have 2 rows with data. After the call there can be 10 rows. — user3944364
– user3944364, Commented Mar 25, 2015 at 11:44

R3tep · Accepted Answer · 2017-06-21 15:49:57Z

6

In the succes of your ajax call use the function push()

product.push([]);

This adds an array at the last index of product. Like that ,the index 10 is created and you have an extra data.

If you want to add a dynamic number of rows, use this code :

var number_of_new_row = 11; // 11 for example, you can use any number >= 0
for(; number_of_new_row--;)
    product.push([]);

Another way

In your ajax return save the new length of your array product in a global variable. And use it before your loop to reset your array and initialize it with the new length.

var lengthArray = 10; // update the value in the callback of your ajax call

And your loop :

var product = [];
for(; lengthArray--;)
    product.push([]);

$('#contextreload ul').each(function(i, ul) {
    //<strike> var product = $(ul).html();  </strike>
    allline = i; 

    $('#reloadajax'+i+' li').each(function(lk, li) {
        var lilk = $(li).html();  
        product[i][lk]=lilk;
        alert(lilk+lk);
        // your code goes here
    });
    // your code goes here
});

edited Jun 21, 2017 at 15:49

answered Mar 25, 2015 at 11:26

R3tep

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3 Comments

user3944364 Over a year ago

I want to rewrite the array. I think my function is wrong with this line product[i][lk]=lilk; . Mabe product[i]=[var,var,var,var]; is right. I need to rethink the loop

R3tep Over a year ago

@user3944364 I added another way in my answer.

user3944364 Over a year ago

Works $('#contextreload ul').each(function(i, ul) { product.push([]); }); Thanks

R3tep · Accepted Answer · 2015-03-26 09:48:20Z

3

Note: this line of your code produces a string, not an array.

var product = $(ul).html();  //returns string not an array

what you need is something like

var product_arr = {}; // an object or 
var product_arr = []; // an array

edited Mar 26, 2015 at 9:48

R3tep

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answered Mar 25, 2015 at 13:01

fedmich

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2 Comments

R3tep Over a year ago

{} defines an object and not an array. [] is more appropriate

fedmich Over a year ago

thats right R3tep. that was what I meant on the 2nd line

Vijay · Accepted Answer · 2015-03-26 10:49:17Z

2

The following code used to declare empty array in javascript

var product_arr = new Array(); //declaring empty array

console.log(product_arr);

answered Mar 26, 2015 at 10:49

Vijay

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Comments

happysailingdude · Accepted Answer · 2020-07-05 09:56:12Z

0

var product = [];

was the answer I was looking for personally

answered Jul 5, 2020 at 9:56

happysailingdude

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