JavaScript Add Values to Multidimensional Array

Question

Hi I am trying to add some values to a multidimensional array using a for loop. This is what I have created so far:

var test1 = [];
var test2 = [];
for (var i = 0; i < top10.length; i++)
{
    test1[i] = i;
    test1[i][0] = top10[i][0];
    test1[i][1] = top10[i][1];
}

This is just returning an empty array. top10 is a multidimensional array which contains:

It can contain more data that's why I need a for loop. I am trying to create 2 multidimensional arrays "test1" and "test2" one will contain "Hinckley Train Station" and "4754" the other will contain "Hinckley Train Station" and "2274".

I can have multiple venues not just "Hinckley Train Station" "4754" "2274" I could also have "London City" "5000" "1000". This is why it is a for loop.

It would be useful to post a subset of the data in `top10` so we can fully replicate your code. — George, Aug 16 '17 at 12:42

Nina Scholz · Accepted Answer · 2017-08-16T13:43:09.310

2

You could push a new array to the wanted parts

var top10 = [
        ["Hinckley Train Station", "4754", "2274"],
        ["London City", "5000", "1000"]
    ],
    test1 = [],
    test2 = [],
    i;

for (i = 0; i < top10.length; i++) {
    test1.push([top10[i][0], top10[i][1]]);
    test2.push([top10[i][0], top10[i][2]]);
}

console.log(test1);
console.log(test2);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Aug 16 '17 at 13:43

answered Aug 16 '17 at 12:46

Nina Scholz

376,160
25
347
392

I have done this but it doesn't create an array inside an array which is what I need – Luke Rayner Aug 16 '17 at 13:23
how the result different from the wanted one? – Nina Scholz Aug 16 '17 at 13:43

Ruan Mendes · Answer 2 · 2017-08-16T13:24:58.067

In this line

test1[i] = i;

You are assigning an integer to be the first element of the outer array. You don't have a 2d array, you have an array of integers

In the following lines:

test1[i][0] = top10[i][0];
test1[i][1] = top10[i][1];

You are assigning properties to an integer, which means they are being boxed but the boxed value is thrown away.

It's hard to tell what you are trying to do, but the following is probably closer. You need to create a new inner array each time through the loop.

for (var i = 0; i < top10.length; i++)
{
    test1[i] = [];
    test1[i][0] = top10[i][0];
    test1[i][1] = top10[i][1];
    // Maybe do something similar with test2
}

JavaScript Add Values to Multidimensional Array

2 Answers2