Number.POSITIVE_INFINITY - JavaScript 编辑

The Number.POSITIVE_INFINITY property represents the positive Infinity value.

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.POSITIVE_INFINITY
Writable	no
Enumerable	no
Configurable	no

Description

The value of Number.POSITIVE_INFINITY is the same as the value of the global object's Infinity property.

This value behaves slightly differently than mathematical infinity:

• Any positive value, including POSITIVE_INFINITY, multiplied by POSITIVE_INFINITY is POSITIVE_INFINITY.
• Any negative value, including NEGATIVE_INFINITY, multiplied by POSITIVE_INFINITY is NEGATIVE_INFINITY.
• Any positive number divided by POSITIVE_INFINITY is positive Zero.
• Any negative number divided by POSITIVE_INFINITY is negative Zero.
• Zero multiplied by POSITIVE_INFINITY is NaN.
• NaN multiplied by POSITIVE_INFINITY is NaN.
• POSITIVE_INFINITY, divided by any negative value except NEGATIVE_INFINITY, is NEGATIVE_INFINITY.
• POSITIVE_INFINITY, divided by any positive value except POSITIVE_INFINITY, is POSITIVE_INFINITY.
• POSITIVE_INFINITY, divided by either NEGATIVE_INFINITY or POSITIVE_INFINITY, is NaN.

You might use the Number.POSITIVE_INFINITY property to indicate an error condition that returns a finite number in case of success. Note, however, that isFinite would be more appropriate in such a case.

Because POSITIVE_INFINITY is a static property of Number, you always use it as Number.POSITIVE_INFINITY, rather than as a property of a Number object you created.

Examples

Using POSITIVE_INFINITY

In the following example, the variable bigNumber is assigned a value that is larger than the maximum value. When the if statement executes, bigNumber has the value Infinity, so bigNumber is set to a more manageable value before continuing.

var bigNumber = Number.MAX_VALUE * 2;

if (bigNumber == Number.POSITIVE_INFINITY) {
  bigNumber = returnFinite();
}

Specifications

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

Browser compatibility

BCD tables only load in the browser

See also

• Number.NEGATIVE_INFINITY
• Number.isFinite()
• Infinity
• isFinite()