js understanding arrow notation ternary operator

Asked May 10 '18 at 20:38

Active May 10 '18 at 20:38

Viewed 58 times

I have the following two functions:

const sections = Object.keys(this.state.obj).map(key => {console.log(key,'x')
  return({
  key,
  title: key,
  // turn array of values into array of objects in the shape {key, value}
  data: toArray(this.state.obj[key]).map(toObject),
})})

const toArray = val => val instanceof Array ? val : [val]

could someone explain what [val] is in the second function? Why are the [] needed?

asked May 10 '18 at 20:38

DCR

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It's an array literal with a single element. Nothing to do with the ternary or arrow function syntax. – Bergi May 10 '18 at 20:39
1

`function toArray(val) { if (val instanceof Array) return val; else return [val]; }`. Should've been `Array.isArray(val)` though. – Bergi May 10 '18 at 20:40
ahh, so we are forcing the return to be an array – DCR May 10 '18 at 20:41
2

Yes, that's what the name `toArray` suggests :-) – Bergi May 10 '18 at 20:42
why is Array.isArray() better than instanceof Array? – DCR May 10 '18 at 20:46
1

@DCR https://stackoverflow.com/questions/22289727/difference-between-using-array-isarray-and-instanceof-array – Barmar May 10 '18 at 20:48

js understanding arrow notation ternary operator

0 Answers0