How to assign value to var conditionally

Question

I am looking for a way to do a conditional assignment of value to a key in an object. In my case i have an old data structure in my json file which is different then the new one so for example now the field is seller1FirstName and before it was seller1FName. What i need is a way to assign the value of this field to a var in my code. I know i could check if one exist and then assign it or if not use the other like this

if (data.seller1FirstName) {
   let mySellerFirstName = data.seller1FirstName
 } else {
   let mySellerFirstName = data.seller1FName
 }

i am hoping there is a cleaner and shorter way to do this

`const mySellerFirstName = data.seller1FirstName ?? data.seller1FName;`? — Sebastian Simon, Sep 21 '21 at 16:26

score 3 · Accepted Answer · edited Sep 21 '21 at 16:37

3

You could use a ternary 'if' operator to do the same thing in only one line:

let mySellerFirstName = data.seller1FirstName ? data.seller1FirstName : data.seller1FName;

edited Sep 21 '21 at 16:37

Dharman

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answered Sep 21 '21 at 16:31

ajzbrun

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score 0 · Answer 2 · answered Sep 21 '21 at 16:36

0

You can use the optional chaining operator in addition to the nullish coalescing operator.

let data = {
  seller1FName : 'value'
}

let newValue = data?.seller1FirstName ?? data.seller1FName;

console.log(newValue);

answered Sep 21 '21 at 16:36

jateen

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3
13

1

This is not strictly the same. `??` will use the second value if the first is `undefined` or `null`. The `if` check in the original would use the second value if the first is falsey (`undefined`, `null`, or `""`). – crashmstr Sep 21 '21 at 16:39

How to assign value to var conditionally

2 Answers2