How to concatenate a variable name

Question

I want the following call to my function

MakeMargin(unit1)

To ouput the following variable ( not a string ! ):

theme.spacing.unit1

I tried the following :

function MakeMargin(props) {
  const output = theme.spacing + props

  return (
    output
  );
}

Vote to close because this question is unclear. Please share i.e: error output — Ele, Jan 31 '18 at 13:03
Possible duplicate of [Dynamically access object property using variable](https://stackoverflow.com/questions/4244896/dynamically-access-object-property-using-variable) — str, Jan 31 '18 at 13:03
Also, take a look [here](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Meta_programming) — Federico klez Culloca, Jan 31 '18 at 13:03
Just to clarify, are you trying to output the content of that variable or the variable itself? I mean, are we talking about metaprogramming? — Federico klez Culloca, Jan 31 '18 at 13:05
Probably the OP wants to pass a String, i.e: `MakeMargin("unit1")` and within `MakeMargin` returns `"theme.spacing" + props`. It's unclear!" — Ele, Jan 31 '18 at 13:06
@ele judging from the comment to faly's answer I'm afraid we are both wrong. — Federico klez Culloca, Jan 31 '18 at 13:08
@FedericoklezCulloca no, the question is asking for concatenation and not for object accessing. It's unclear. — Ele, Jan 31 '18 at 13:09
I wasn't sure that concatenation was the right term here. Thanks everybody — Romainpetit, Jan 31 '18 at 13:09

score 2 · Accepted Answer · answered Jan 31 '18 at 13:03

2

It should be:

function MakeMargin(props) {
    return theme.spacing[props]
}

answered Jan 31 '18 at 13:03

Faly

The OP wants to concatenate. It's unclear what the OP has asked. – Ele Jan 31 '18 at 13:04
That's what I was looking for, thanks ! – Romainpetit Jan 31 '18 at 13:07
@Romainpetit that's not what you've asked. This answer doesn't answer what you wrote in your question. – Ele Jan 31 '18 at 13:09

1 Answers1