Angular4 - custom pipe creation

Question

I cant understand one thing in the code below - why (limit) is in parenthesis?

import { Pipe, PipeTransform } from '@angular/core'

@Pipe ({
 name: 'summary'
})

export class SummaryPipe implements PipeTransofm {
 transform(value: string, limit?: number) {
  if (!value) 
   return null;

  let specificLimit = (limit) ? limit : 50;
  return value.substr(0, specificLimit);
 }
}

Thanks

Here a screenshot, to be sure I copied it right:

are you sure you copied that part (limit) ? : 50; correctly? it seems to be an incorrect syntax — Max Koretskyi
– Max Koretskyi, Commented Jul 14, 2017 at 6:31
@Maximus, I am sure, I added a screenshot from the video of the Tutorial, from Udemy.com - udemy.com/angular-2-tutorial-for-beginners — Julius Dzidzevičius
– Julius Dzidzevičius, Commented Jul 14, 2017 at 6:33
yeah, that's a different case, it is now correct syntax. the parenthesis are just a style preference, they make more sense for me when there's an expression inside like (limit === 3) ? limit : 50 — Max Koretskyi
– Max Koretskyi, Commented Jul 14, 2017 at 6:40

Chrillewoodz · Accepted Answer · 2017-07-14 06:47:04Z

1

This code will throw syntax error because the true condition lacks an expression. The parenthesis are not needed in your example, you could write it like

let specificLimit = limit ? : 50;

too but like I said this will throw an error. You must give it a value for when the ternary yields true so something like:

let specificLimit = limit ? limit : 50;

edited Jul 14, 2017 at 6:47

answered Jul 14, 2017 at 6:31

Chrillewoodz

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