isFinite()

isFinite(value): value is number

Checks if value is a finite number.

DEPRECATED

Use Number.isFinite() directly instead.

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Parameters

value: unknown

The value to check.

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Returns: value is number

true if value is a finite number, else false.

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See Also

• Number.isFinite() - MDN
• Browser support - Can I Use

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Since

2.0.0

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Also known as

isFinite (Lodash, es-toolkit) · ❌ (Remeda, Radashi, Ramda, Effect, Modern Dash, Antfu)

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Example

// ❌ Deprecated approach
isFinite(42);        // => true
isFinite(Infinity);  // => false
isFinite(NaN);       // => false
isFinite('42');      // => false

// ✅ Recommended approach
Number.isFinite(42);        // => true
Number.isFinite(Infinity);  // => false
Number.isFinite(NaN);       // => false
Number.isFinite('42');      // => false

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How it works?

Checks if value is a finite number.

Type Narrowing

Common Checks

Value	Result
42	true
3.14	true
Infinity	false
-Infinity	false
NaN	false
'42'	false

Deprecated: Use Number.isFinite() directly.

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Use Cases

Validate finite number 📌

Check if value is a finite number.

#finite#number#validate#infinity

Number.isFinite(42);        // true
Number.isFinite(Infinity);  // false
Number.isFinite(NaN);       // false

Guard calculations

Ensure calculation results are valid.

#guard#calculation#safe#division

const result = a / b;
if (Number.isFinite(result)) {
  return result;
}
return 0;  // fallback for Infinity/NaN