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# JavaScript NEGATIVE_INFINITY and POSITIVE_INFINITY Properties This tutorial describes the NEGATIVE_INFINITY and POSITIVE_INFINITY properties of JavaScript's Number object. The value of NEGATIVE_INFINITY and POSITIVE_INFINITY are read-only: they cannot be changed by your scripts; they are returned by JavaScript whenever a function or operation returns a number larger than the MAX_VALUE the JavaScript interpreter can handle.

POSITIVE_INFINITY vs. MAX_VALUE — The value of the MAX_VALUE property is the largest number your JavaScript interpreter can handle. Larger value will be viewed as POSITIVE_INFINITY.

NEGATIVE_INFINITY vs. MIN_VALUE — The value of the MIN_VALUE property is the smallest (closest to zero) number your JavaScript interpreter can handle, while NEGATIVE_INFINITY is the largest negative number the JavaScript interpreter can represent.

## JavaScript Number Scale

The number scale below illustrate where JavaScript's number property constants fit in. It is useful to remember that MIN_VALUE is not the largest negative number: it is the smallest positive number JavaScript can represent. ## Generating an Infinite Result with JavaScript Numberss

We know that JavaScript will return POSITIVE_INFINITY whenever it should return a number larger than the value it can handle (MAX_VALUE). The script below attempts to add MAX_VALUE to itself, which by definition will be out of range. (MAX_VALUE is the largest number JavaScript can handle.)

`alert( Number.MAX_VALUE + Number.MAX_VALUE );`

Since the value of MAX_VALUE is finite, we know that doubling it cannot yield an infinite result. Yet JavaScript returned: The JavaScript keyword Infinity points to the same internal value as POSITIVE_INFINITY. For practical purposes, "`Infinity`" can be used interchangeably with "`Number.POSITIVE_INFINITY`" in your scripts.

The script below illustrate how the JavaScript interpreter understands the concept of infinity (anything out of bound is infinite).

`alert( Number.NEGATIVE_INFINITY === -2 * Number.MAX_VALUE );`

In other words: according to the JavaScript interpreter, is negative infinity identical to the negative double of the finite MAX_VALUE property? ### Number.POSITIVE_INFINITY vs. Infinity

Infinity is a JavaScript reserved keyword introduced in ECMAScript version 2; it does not supersede Number.POSITIVE_INFINITY, and can be used in its place. Both point to the exact same internal value, as demonstrated below.

`// Check if Infinity is identical to POSITIVE_INFINITYalert( Infinity === Number.POSITIVE_INFINITY );// The same holds true for negative Infinityalert( -Infinity === -Number.POSITIVE_INFINITY );`

Both lines of script return the same result: ## Test the NEGATIVE_INFINITY and POSITIVE_INFINITY Properties

Interactively test the NEGATIVE_INFINITY and POSITIVE_INFINITY properties by editing the JavaScript code below and clicking the Test NEGATIVE_INFINITY and POSITIVE_INFINITY button.

Browser support: NEGATIVE_INFINITY & POSITIVE_INFINITY    