Validation/Since 1.38.0

isInteger

Checks whether a value is an integer number.

isInteger(value):boolean

Behavior

The function delegates directly to Number.isInteger. It returns true only when the value is a number whose value is an integer.

The function is a TypeScript type guard. When it returns true, TypeScript narrows the value from unknown to number.

valueunknownrequired

The value to check.

boolean

Returns true when the value is an integer number; otherwise returns false.

Returns true for positive, negative, and zero integer values.

TypeScript

isInteger(42);
// true

isInteger(-10);
// true

isInteger(0);
// true

Decimal numbers are not considered integers.

TypeScript

isInteger(4.5);
// false

isInteger(-2.75);
// false

Strings, booleans, null, and other non-number values return false.

TypeScript

isInteger("42");
// false

isInteger(true);
// false

isInteger(null);
// false

NaN and Infinity are not integers.

TypeScript

isInteger(NaN);
// false

isInteger(Infinity);
// false

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