Typescript name of key in Object

Question

Suppose we have object like this:

foo = {
   "currency": "dollar"
}

Is it possible to check if value of object exists and is equal to dollar? For example:

const bar = currency;

So how can we pass the value of bar to foo path? Or use any syntax that should work as $bar? I don't want to pass $bar as a path name but a value of bar as a path.

foo.$bar? true: false
in result  foo.currency === true or false

Or even is it possible to have another object like:

anotherobject.anotherpath.$(getKey(foo))

to get object like anotherobject.anotherpath.currency?
Hope it's clear enough to understand

Are you maybe looking for foo[bar]? Like in foo[bar] == "dollar"? — Aioros
– Aioros, Commented Jan 15, 2019 at 21:19
@Aioros, mate I don't want to check the value, but if the specific path exists. This way I want to be sure if path foo.$bar exists, where $bar = currency. — Chilled_mimosa
– Chilled_mimosa, Commented Jan 15, 2019 at 21:23
you can do if (bar in foo && foo[bar] === 'dollar') where bar = 'currency' developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Robbie Milejczak
– Robbie Milejczak, Commented Jan 15, 2019 at 21:29

Amats · Accepted Answer · 2019-01-15 21:28:23Z

1

Objects act a bit like arrays in that you can access values stored in a certain index using the bracket notation - but in this case, using the key or field in place of the numeric index.

So you can:

const foo = { "currency": "dollar" };
const bar = "currency"

if (foo[bar] == "dollar") { /* do something */ }

If you want to check if the 'bar' property exists in the foo object, you can also do:

const foo = { "currency": "dollar" };
const bar = "currency"

// will check if foo.bar exists
if (foo.hasOwnProperty(bar)) {/* do something */}

edited Jan 15, 2019 at 21:28

answered Jan 15, 2019 at 21:26

Amats

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2 Comments

Chilled_mimosa Over a year ago

As I've mentioned, I don't want to check if value of 'currency' is 'dollar' but I want to check if foo.$bar exists, where $bar = currency :)

Amats Over a year ago

the hasOwnProperty function will check if the foo object has the 'currency' field, is that what you needed?

Aioros · Accepted Answer · 2019-01-15 21:29:42Z

1

var foo = {
   "currency": "dollar"
};
var bar = "currency";

Check if the key exists:

if (foo[bar])

Or:

if (foo.hasOwnProperty(bar))

Check if property has the right value

if (foo[bar] == "dollar")

answered Jan 15, 2019 at 21:29

Aioros

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Comments

IMParasharG · Accepted Answer · 2019-01-15 21:38:45Z

0

You can use Object.values():

example is below:

var foo = {
   "currency": "dollar"
};
var bar = "currency";


console.log(Object.values(foo).indexOf(bar) >= 0); //false
console.log(Object.keys(foo).indexOf(bar) >= 0); //true

answered Jan 15, 2019 at 21:38

IMParasharG

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