What is infinity in javascript?

Infinity is a property of the global object , or in other words, a variable in global scope. The initial value of Infinity is Number.POSITIVE_INFINITY . 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.

alert( Number.MAX_VALUE + Number.MAX_VALUE ); //infinity alert( -2 * Number.MAX_VALUE ); // Negative infinity

POSITIVE_INFINITY is displayed when a number exceeds the upper limit of the floating point numbers, which is 1.797693134862315E+308 while NEGATIVE_INFINITY is displayed when a number exceeds the lower limit of the floating point numbers, which is -1.797693134862316E+308.

alert(Math.pow(10, 1000)); /* Infinity */ alert(Math.log(0) ); /* Negative Infinity */

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. 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. 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 ); //true

The above script return "true" because JavaScript interpreter understands the concept, the negative infinity identical to the negative double of the finite MAX_VALUE property.

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