Number.EPSILON - JavaScript 编辑

The Number.EPSILON property represents the difference between 1 and the smallest floating point number greater than 1.

You do not have to create a Number object to access this static property (use Number.EPSILON).

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.

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.

Property attributes of Number.EPSILON
Writable	no
Enumerable	no
Configurable	no

Description

The EPSILON property has a value of approximately 2.2204460492503130808472633361816E-16, or 2-52.

Examples

Testing equality

x = 0.2;
y = 0.3;
z = 0.1;
equal = (Math.abs(x - y + z) < Number.EPSILON);

Polyfill

if (Number.EPSILON === undefined) {
    Number.EPSILON = Math.pow(2, -52);
}

Specifications

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

Browser compatibility

BCD tables only load in the browser

See also

• The Number object it belongs to