isInteger()

isInteger(value): value is number

Checks if value is an integer.

DEPRECATED

Use Number.isInteger() 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 an integer, else false.

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See Also

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

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Since

2.0.0

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Also known as

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

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Example

// ❌ Deprecated approach
isInteger(42);      // => true
isInteger(42.0);    // => true
isInteger(42.5);    // => false
isInteger('42');    // => false

// ✅ Recommended approach
Number.isInteger(42);      // => true
Number.isInteger(42.0);    // => true
Number.isInteger(42.5);    // => false
Number.isInteger('42');    // => false

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How it works?

Checks if value is an integer.

Type Narrowing

Common Checks

Value	Result
42	true
42.0	true
42.5	false
'42'	false
Infinity	false

Deprecated: Use Number.isInteger() directly.

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Use Cases

Validate integer 📌

Check if value is an integer.

#integer#number#validate#whole

Number.isInteger(42);    // true
Number.isInteger(42.0);  // true
Number.isInteger(42.5);  // false

Validate quantity

Ensure quantities are whole numbers.

#quantity#count#validation

function setQuantity(qty: number) {
  if (!Number.isInteger(qty) || qty < 0) {
    throw new Error('Invalid quantity');
  }
  this.quantity = qty;
}