how to check if a collection has value in typescript

Question

I wanted to check whether a collection has value or not, I did like below and its working. Please suggest if we have any better approach...

I am checking if data is [] then do nothing, else do something

let data = await this.http.post(_postsURL, {
  headers: this.getPostAPIHeader()
}).toPromise();
if (data[0]) {
  console.log("response yes ");
} else {
  console.log("response no ");
}

The better approach would be to check data.length. data[0] might contain a falsy value and break your check — Jonathan, Jul 09 '18 at 17:04
`if (!data || !data.length) { console.log('empty'); } else { console.log('has values'); }` — lealceldeiro, Jul 09 '18 at 17:06
Your text says you compare `data` to `[]`, but your code checks `data[0]` for truthiness. If you want to compare `data` to `[]` then use `if (data == [])`, although as others have noted, it's better to check the length. See [Check if array is empty / does not exist. JS](https://stackoverflow.com/q/24403732) — Heretic Monkey, Jul 09 '18 at 17:10

score 0 · Answer 1 · answered Jul 09 '18 at 19:27

0

try this instead:

if (data.length===0 || !date) {
  console.log("response yes ");
} else {
  console.log("response no ");
}

answered Jul 09 '18 at 19:27

fr97

1

score -1 · Answer 2 · answered Aug 26 '23 at 00:13

-1

if (data !==undefined && data.length >0) {
  console.log("response yes ");
} else {
  console.log("response no ");
}

answered Aug 26 '23 at 00:13

Joon w K

777
1
6
27

how to check if a collection has value in typescript

2 Answers2