Constant                    Description
    --------------------------  -----------------------------------------------------------------------------------------
    Infinity                    Represents positive infinity
    Number.MAX_VALUE            The largest number able to be represented in JavaScript 
    Number.MIN_VALUE            The smallest or most negative number able to be represented in JavaScriptNumber.
    NEGATIVE_INFINITY           A value representing negative infinity
    Number.POSITIVE_INFINITY    A value representing positive infinity
    
Script:
document.write("Infinity=")
var a = Infinity;
document.write(a);
document.write("<br>")

document.write("Number.MAX_VALUE=")
var b = Number.MAX_VALUE;
document.write(b);
document.write("<br>")

document.write("Number.MIN_VALUE=")
var c = Number.MIN_VALUE;
document.write(c);
document.write("<br>")

document.write("Number.NEGATIVE_INFINITY=")
var d = Number.NEGATIVE_INFINITY;
document.write(d);
document.write("<br>")

document.write("Number.POSITIVE_INFINITY=")
var e = Number.POSITIVE_INFINITY;
document.write(e); document.write("<br>")


Funcionamento: