isSafeInteger()

isSafeInteger(value): value is number

Checks if value is a safe integer.

A safe integer is an integer that can be exactly represented as an IEEE-754 double precision number, and whose IEEE-754 representation cannot be the result of rounding any other integer to fit the IEEE-754 representation.

DEPRECATED

Use Number.isSafeInteger() 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 safe integer, else false.

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See Also

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

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Since

2.0.0

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Also known as

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

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Example

// ❌ Deprecated approach
isSafeInteger(42);                        // => true
isSafeInteger(9007199254740991);          // => true (MAX_SAFE_INTEGER)
isSafeInteger(9007199254740992);          // => false

// ✅ Recommended approach
Number.isSafeInteger(42);                 // => true
Number.isSafeInteger(9007199254740991);   // => true
Number.isSafeInteger(9007199254740992);   // => false

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How it works?

Checks if value is a safe integer (exactly representable in IEEE-754).

Safe Integer Range

Common Checks

Value	Result
42	true
9007199254740991	true (MAX_SAFE_INTEGER)
9007199254740992	false
3.14	false
Infinity	false

Deprecated: Use Number.isSafeInteger() directly.

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Use Cases

Validate safe integer 📌

Check if value is a safe integer (within IEEE-754 precision).

#safe#integer#precision#validate

Number.isSafeInteger(42);                 // true
Number.isSafeInteger(9007199254740991);   // true (MAX_SAFE_INTEGER)
Number.isSafeInteger(9007199254740992);   // false

Guard ID operations

Ensure IDs don't lose precision.

#id#precision#database#bigint

function processId(id: number) {
  if (!Number.isSafeInteger(id)) {
    throw new Error('ID too large, use BigInt');
  }
  return fetchRecord(id);
}