A number that is larger than the largest floating point number.
Returns an initial value of Number.POSITIVE_INFINITY.
Divisions by zero will give you Infinity. Divisions by negative zero will give you -Infinity.
42 / 0; // Infinity 42 / 0; // -Infinity
Everything beyond Infinity remains Infinity
Infinity * Infinity; // Infinity
If an arithmetic overflow occurs, Infinity is also returned
Math.pow(2, 1024); // Infinity
The Infinity constant is a member of the Global object, and is made available when the scripting engine is initialized.
Negative Infinity (-Infinity) is smaller than the smallest floating point number and returns a value of Number.NEGATIVE_INFINITY.
This value behaves mathematically like infinity; for example, anything multiplied by Infinity is Infinity, and anything divided by Infinity is 0.
Infinity subtracted by Infinity will return NaN
The isFinite() function can be used to check if a given value is a finite number
Microsoft Developer Network: Article