Number.isFinite() - JavaScript 编辑

The Number.isFinite() method determines whether the passed value is a finite number — that is, it checks that a number is neither positive nor negative Infinity, since JavaScript has both.

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The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

Number.isFinite(value)

Parameters

value

The value to be tested for finiteness.

Return value

A Boolean indicating whether or not the given value is a finite number.

Description

In comparison to the global isFinite() function, this method doesn't first convert the parameter to a number. This means only values of the type number and are finite return true.

Examples

Using isFinite

Number.isFinite(Infinity);  // false
Number.isFinite(NaN);       // false
Number.isFinite(-Infinity); // false

Number.isFinite(0);         // true
Number.isFinite(2e64);      // true

Number.isFinite('0');       // false, would've been true with
                            // global isFinite('0')
Number.isFinite(null);      // false, would've been true with
                            // global isFinite(null)

Polyfill

if (Number.isFinite === undefined) Number.isFinite = function(value) {
    return typeof value === 'number' && isFinite(value);
}

Specifications

Specification
ECMAScript (ECMA-262) The definition of 'Number.isInteger' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• The Number object it belongs to.
• The global function isFinite.