Dynamic Concatenation in Javascript Array

Question

Let's say I have an array of data and a variable (or multiple variables)

var i = 1;
var arr = {
        1: ['whatever' + i,'there are ' + i + ' dogs in the yard.', etc], 
    }

Is there a way to dynamically update the variable(s) in the array later on in a function?

So

function start() {
i++;
alert(arr[1][0]);
}

Would output "whatever2" instead of "whatever1"

What do you mean with 'update the variable'?. Please, explain it better — Danilo Valente
– Danilo Valente, Commented May 10, 2012 at 1:12
Your question is not clear... if you think about changing i later on, that's not possible. 'whatever' + i and 'there are ' + i + ' dogs in the yard.' are evaluated when the array is defined, i.e. the value of i is determined at that moment and that value is concatenated with the other string. — Felix Kling
– Felix Kling, Commented May 10, 2012 at 1:14

Joseph · Accepted Answer · 2012-05-10 01:14:20Z

3

You could have an array and push() stuff you need, but when the string is made, it won't change anymore.

var array = ['whatever',i,'there are ',i,' dogs in the yard.'];
array.push('more stuff');
array.push('even more stuff');
var string = array.join('')
//string = 'whatever[whatever "i" is during join]there are[whatever "i" is during join]dogs in the yard.more stuffeven more stuff'

answered May 10, 2012 at 1:14

Joseph

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Comments

Jacob · Accepted Answer · 2012-05-10 02:01:43Z

1

You could use functions instead:

var i = 1;
var arr = {
    1: [
        function() { return 'whatever' + i },
        function() { return 'there are ' + i + ' dogs in the yard.' },
        function() { return 'etc' }
    ], 
}:

Which would change your calls to:

function start() {
    i++;
    alert(arr[1][0]());
}

answered May 10, 2012 at 2:01

Jacob

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1 Comment

Stephen Over a year ago

Clever. This is the closest to what I wanted. Thanks!

Danilo Valente · Accepted Answer · 2012-05-10 01:17:36Z

1

Try this code:

var arr = function(i){
    return {
        1: ['whatever' + i,'there are ' + i + ' dogs in the yard.', etc],
    }
}
var anyNumber = 1;
var updatedVar = arr(anyNumber);

answered May 10, 2012 at 1:17

Danilo Valente

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