Question 226475 in Javascript Question posted in
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Javascript – Why is an empty string rendered in vue.js template considered truthy?

Why does an empty string in a vue template return as truthy?

<div>{{ "" ?? "empty string is not truthy" }}</div>

This will just display the empty string. I have a bunch of empty string fields which I can’t check with the nullish coalescing operator (??) but instead have to use ternaries:

<div>{{ "" ? "string empty" : "string not empty" }}</div>

Shouldn’t "" ?? be faulty?

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2

Answers


  1. 0

    "" is not null nor undefined. Just like 0. These are just ‘falsey’, so won’t work with ??:

    // Not null or undefined
console.log("" ?? "If my empty string is null or undefined, then log this, else log empty string");
// Not null or undefined
console.log(0 ?? "If 0 is null or undefined, then log this, else log 0");
// Actually null or undefined
console.log(undefined ?? "If undefined is null or undefined, then log this, else log undefined");
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  2. 0

    The Nullish coalescing operator (??) tests if a value is not null or undefined, not if it is truthy.

    "" is a falsy value, but it isn’t null and it isn’t undefined.

    Use the Logical OR (||) operator to test for truthiness.

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