JavaScript Number NEGATIVE_INFINITY Property

What You’ll Learn

Number.NEGATIVE_INFINITY is a static data property on Number (same API as MDN Number.NEGATIVE_INFINITY). It is the negative Infinity value — the same as -Infinity and -Number.POSITIVE_INFINITY. You get it when math overflows past -MAX_VALUE, or from expressions like -1 / 0. This tutorial covers detection, IEEE-754 rules, five examples, and try-it labs.

Introduction

IEEE-754 floating point includes two signed infinities. Number.NEGATIVE_INFINITY is how JavaScript names negative infinity — smaller than every finite Number, including -Number.MAX_VALUE.

It is the same value as -Infinity ((Number.NEGATIVE_INFINITY === -Infinity), and also equals -Number.POSITIVE_INFINITY. Prefer the Number. form so infinity stays with other Number constants, and because it is non-writable.

This page is part of JavaScript Number Properties. Related tools include Number.POSITIVE_INFINITY, Number.isFinite(), and Number.MAX_VALUE.

Understanding the NEGATIVE_INFINITY Property

Negative infinity is not “a huge negative finite number” — it is a special IEEE-754 value. Once a result becomes -Infinity, further math often stays infinite (or becomes NaN in indeterminate cases like -Infinity / -Infinity).

• It is a constant number, not a method.
• Same value as -Infinity and -Number.POSITIVE_INFINITY.
• Less than every finite Number: Number.NEGATIVE_INFINITY < -Number.MAX_VALUE.
• Detect with === Number.NEGATIVE_INFINITY or !Number.isFinite(x).

📝 Syntax

General form of the static property Number.NEGATIVE_INFINITY:

Number.NEGATIVE_INFINITY

Value

The same as the negative value of the global Infinity property (-Infinity).

Property attributes

Common patterns

Number.NEGATIVE_INFINITY;                  // -Infinity
Number.NEGATIVE_INFINITY === -Infinity;    // true
Number.NEGATIVE_INFINITY === -Number.POSITIVE_INFINITY; // true
-Number.MAX_VALUE * 2;                     // -Infinity
-1 / 0;                                    // -Infinity

Number.isFinite(Number.NEGATIVE_INFINITY); // false

function checkNumber(smallNumber) {
  if (smallNumber === Number.NEGATIVE_INFINITY) {
    return "Process number as -Infinity";
  }
  return smallNumber;
}

Examples Gallery

Examples follow MDN Number.NEGATIVE_INFINITY patterns. Use View Output or Try It Yourself for each case.

Number.NEGATIVE_INFINITY;
Number.NEGATIVE_INFINITY === -Infinity;  // true
Number.NEGATIVE_INFINITY === -Number.POSITIVE_INFINITY;  // true

-Infinity
true
true

-Number.MAX_VALUE * 2;  // -Infinity

-Infinity

function checkNumber(smallNumber) {
  if (smallNumber === Number.NEGATIVE_INFINITY) {
    return "Process number as -Infinity";
  }
  return smallNumber;
}

checkNumber(-Number.MAX_VALUE);      // -1.7976931348623157e+308
checkNumber(-Number.MAX_VALUE * 2);  // "Process number as -Infinity"

-1.7976931348623157e+308
Process number as -Infinity

-1 / 0;                                  // -Infinity
-1 / 0 === Number.NEGATIVE_INFINITY;     // true
1 / Number.NEGATIVE_INFINITY;            // -0

-Infinity
true
0

typeof Number.NEGATIVE_INFINITY;                 // "number"
Number.isFinite(Number.NEGATIVE_INFINITY);       // false
Number.NEGATIVE_INFINITY < -Number.MAX_VALUE;    // true

number
false
true

🚀 Common Use Cases

• Overflow detection — compare results to Number.NEGATIVE_INFINITY.
• Open lower bounds — algorithms sometimes use −∞ as an initial minimum.
• Graphics / physics — represent unbounded negative extents carefully.
• Validation — reject non-finite inputs with Number.isFinite.
• Not for errors by default — MDN notes NaN is often a better failure signal.
• Teaching IEEE-754 — show that -1 / 0 is defined as -Infinity in JS.

📝 Notes

• This is a static property — use Number.NEGATIVE_INFINITY only.
• Do not write Number.NEGATIVE_INFINITY() — it is not a function.
• Number.NEGATIVE_INFINITY === -Infinity is true.
• 0 * -Infinity and -Infinity / -Infinity are NaN.
• Positive twin: Number.POSITIVE_INFINITY.
• Prefer Number.isFinite() to reject all non-finite values.

💡 Best Practices