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Kaziu
Kaziu

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Difference between Logical OR (||) and Nullish coalescing operator(??)

#javascript

Have you came across like this situation ?

obj.name ? obj.name : "I don't know"
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If you so, better write code like that

obj.name || "I don't know"
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|| is called Locgical OR. When left-hand is undefined or null returns right-hand

🤔 Is it the same as ??

?? is called Nullish coalescing operator, it's like Logical OR except falsy values like "", 0

// example const obj = { zero: 0, one: 1, emptyString: '', null: null, undefined: undefined, } console.log(obj.zero || 'Hello')// Hello ⭐ console.log(obj.zero ?? 'Hello')// 0 console.log(obj.one || 'Hello')// 1 console.log(obj.one ?? 'Hello')// 1 console.log(obj.emptyString || 'Hello')// Hello ⭐ console.log(obj.emptyString ?? 'Hello')// "" console.log(obj.null || 'Hello')// Hello console.log(obj.null ?? 'Hello')// Hello console.log(obj.undefined || 'Hello')// Hello console.log(obj.undefined ?? 'Hello')// Hello
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So the reason why I wrote you should use || is that normally you just need to recognise "undefined" or "null" in that case, not falsy value.

it's just my opinion and of course it depends on situation!

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