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isFinite()

isFinite(value): value is number

Checks if value is a finite number.

DEPRECATED

Use Number.isFinite() directly instead.

Parameters​

value: unknown​

The value to check.

Returns: value is number​

true if value is a finite number, else false.

See Also​

Since​

2.0.0

Also known as​

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

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

How it works?​

Checks if value is a finite number.

Type Narrowing​

Common Checks​

ValueResult
42 true
3.14 true
Infinity false
-Infinity false
NaN false
'42' false

Deprecated: Use Number.isFinite() directly.

Use Cases​

Validate finite number 📌​

Check if value is a finite number.

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

Guard calculations​

Ensure calculation results are valid.

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