Not able to get JSON value dynamically

Question

I am working on the following snippet. Why am I not able to get the

let node = 'Em2';
console.log(data.node.c2);

work? As you can see I am able to get data while passing data.Em2.c1 but a dynamic format like this let node = 'Em2'; console.log(data.node.c2); I am getting this error

TypeError: Cannot read property 'c2' of undefined

Code:

var data ={
   "Em1": { "c1":"#FFF", "c2":"#EEE" },
   "Em2": { "c1":"#DDD", "c2":"#ooo" }
}


let node = 'Em2';

console.log(data.Em2.c1);
console.log(data.node.c2);

var data ={
   "Em1": { "c1":"#FFF", "c2":"#EEE" },
   "Em2": { "c1":"#DDD", "c2":"#ooo" }
}


let node = 'Em2';

console.log(data.Em2.c1);
console.log(data.node.c2);

Alesj · Accepted Answer · 2018-09-28T00:13:46.640

2

Use square braces [] to access object member via variable

var data ={
   "Em1": { "c1":"#FFF", "c2":"#EEE" },
   "Em2": { "c1":"#DDD", "c2":"#ooo" }
}


let node = 'Em2';

console.log(data.Em2.c1);
console.log(data[node].c2);

Similar question: how to access object property using variable

edited Sep 28 '18 at 00:13

answered Sep 28 '18 at 00:06

Alesj

5,581
1
16
33

Thanks Alex but why `[]` ?! – Mona Coder Sep 28 '18 at 00:07
1

@Mona if you don't use square braces, js tries to use named property `node` in your object, not property named in variable `node` – Alesj Sep 28 '18 at 00:11

score 0 · Answer 2 · answered Sep 28 '18 at 00:06

0

Instead of console.log(data.node.c2), try console.log(data[node][c2])

answered Sep 28 '18 at 00:06

Paul McLoughlin

2,174
2
15
23

Not able to get JSON value dynamically

2 Answers2