Define variable and check if it's null at once in Javascript

Question

Is it possible simplify this

var element = document.getElementById('myElement');
if(element)
  element.addEventListener('click', (e) => { ... });

into something like this?

if(var element = document.getElementById('myElement'))
  element.addEventListener('click', (e) => { ... });

Thank you.

Why define a variable at all, instead of document.getElementById('myElement')?.addEventListener()? — VLAZ
– VLAZ, Commented Apr 11, 2022 at 15:05
I'd venture that the clarity of your first example trumps other approaches, even the optional chaining approach suggested by others. By packing multiple operations into the smallest footprint, readability suffers and debugging becomes harder. — spender
– spender, Commented Apr 11, 2022 at 15:12
I'm fairly sure that you don't have a requirement for declaring the variable, but it would be nice if you could confirm that a simplification that adds an event listener to the element if it exists is all you are looking for and that you don't actually have a requirement to also have an element variable declared. Right? — Wyck
– Wyck, Commented Apr 11, 2022 at 15:47

Unmitigated · Accepted Answer · 2022-04-11 15:06:03Z

5

You can use optional chaining.

The ?. operator is like the . chaining operator, except that instead of causing an error if a reference is nullish (null or undefined), the expression short-circuits with a return value of undefined.

document.getElementById('myElement')?.addEventListener('click', (e) => { ... });

answered Apr 11, 2022 at 15:06

Unmitigated

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