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Number.EPSILON

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).

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

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

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

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

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Number.EPSILON' in that specification.	Standard	Initial definition.
ECMAScript Latest Draft (ECMA-262) The definition of 'Number.EPSILON' in that specification.	Draft

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	Yes	Yes	25	No	Yes	9

Feature	Android webview	Chrome for Android	Edge mobile	Firefox for Android	Opera Android	iOS Safari	Samsung Internet
Basic support	Yes	Yes	Yes	25	Yes	9	?