How can I made new array from firsts elements of arrays from an array

Saurabh Agrawal 2019-12-05 18:03

Try this:

let arr = [["1", 2], ["3", 2], ["6", 2]];
let res = arr.map(val => {
    return val[0]
})
console.log(res);

mplungjan 2019-12-05 18:02:47

arr.map(val => val[0])

Saurabh Agrawal 2019-12-05 18:04:07

@mplungjan edited :). Btw just want to know what was the issue with that?

T.J. Crowder 2019-12-05 18:08:51

@SaurabhAgrawal - I think mplungjan was pointing out that you can use a concise arrow function there instead of a verbose one: .map(val => val[0]). (Yes, the () you edited out are optional as well, but I don't think that was the main point.)

T.J. Crowder 2019-12-05 18:13:54

@SaurabhAgrawal - No, they do not. They're purely part of the syntax of an arrow function parameter list. They're optional when there's exactly one parameter. It makes no different whatsoever to the execution of the function.

Rayon 2019-12-05 18:14:03

@SaurabhAgrawal - I suppose, he meant Extra () was not needed as you were using only single argument :)

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