Calling a function using variable concatenation

Question

I have an array. Suppose the array is:

var group10 = ['as', '323fsd', 'asdasd', '43ssdf'];

I am passing the array into a function along with an array element so as to remove it from the array. If it removes, it will return true, otherwise, not.

function removeElem(element, array){
    var index = array.indexOf(element);
    if (index > -1) {
        array.splice(index, 1);
        return true;
    }
}

The tricky part is, I'm getting numeric variables dynamically from another function and it's returning either 1 or 2 or .......... 10

If it returns 1, then I want to deal with group1. If it returns 2, I want to deal with group2.

Since the name group is constant, I'm concatenating it with the variable it's returning and passing the whole into the function. But, unfortunately, a string is getting passed.

var arr = 'group'+10;

if( removeElem('323fsd', arr)) {
    console.log(group10);
} else {
    console.log('fail');
}

So, how is it possible to dynamically concatenating and passing the array as a whole into the function?

try eval(arr) so it can be treated as a variable not a string — Ryad Boubaker
– Ryad Boubaker, Commented Nov 24, 2016 at 11:03
Possible duplicate of How to use a string as a variable name in Javascript? — Mahi
– Mahi, Commented Nov 24, 2016 at 11:04
please explain "I'm getting numeric variables dynamically from another function" and where the variables get declared and how they get initialized. — Nina Scholz
– Nina Scholz, Commented Nov 24, 2016 at 12:00
Any time you find yourself using numeric variables like this, you should be using an array instead. — Barmar
– Barmar, Commented Nov 24, 2016 at 12:21

Vikrant · Accepted Answer · 2016-11-24 11:09:11Z

2

eval() is a possible solution so the variable will be treated as a variable if exists in the same name

var group10 = ['as', '323fsd', 'asdasd', '43ssdf'];
var arr = 'group' + 10;

if(removeElem('323fsd', eval(arr))) {
    console.log(group10);
} else {
    console.log('fail');
}

edited Nov 24, 2016 at 11:09

Vikrant

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answered Nov 24, 2016 at 11:05

Ryad Boubaker

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3 Comments

Mahi Over a year ago

i suggest you to don't use eval it's like evil. that will make your code hell

Ryad Boubaker Over a year ago

No sir that's why js has eval it's for such occasions and the most important part is that the eval is not getting it's param from a user input.. there is another alternative which is Using window[varname] but it has the side-effect of introducing global variables, which might not be wanted.

Mahi Over a year ago

stackoverflow.com/questions/86513/…

prasanth · Accepted Answer · 2016-11-24 11:13:17Z

0

Try this:

Declare the array like this array = window[array];.Because the string not allowed directly converted into function or array.

var group10 = ['as', '323fsd', 'asdasd', '43ssdf'];
function removeElem(element, array){
  array = window[array];
 var index = array.indexOf(element);
 
  if (index > -1) {
                    array.splice(index, 1);
                    return true;
                }
 }

 var arr = 'group'+10;
 if( removeElem('323fsd', arr) ){
        console.log(group10);
    }else{
        console.log('fail');
    }

answered Nov 24, 2016 at 11:13

prasanth

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Comments

Nina Scholz · Accepted Answer · 2016-11-25 07:56:24Z

0

A proposal for using an array with the variables' name (assuming all variables are declared in advance).

function removeElem(element, arrayNo) {
    var groups = [group1, group2, group3, group4, group5, group6, group7, group8, group9, group10],
        index = groups[arrayNo - 1)].indexOf(element);

    if (index > -1) {
        groups[arrayNo - 1)].splice(index, 1);
        return true;
    }
}

answered Nov 25, 2016 at 7:56

Nina Scholz

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