Number Prototype Methods

Number.prototype.valueOf()

Returns the primitive value of the specified object. Called automatically when the object is treated as a primitive other than a string, it overrides the Object.prototype.valueOf()method.

Number.prototype.toExponential()

Returns a string representing the number in exponential notation.

Number.prototype.toFixed()

Returns a string representing the number in fixed-point notation.

Number.prototype.toPrecision()

Returns a string representing the number to a specified precision in fixed-point or exponential notation.

Number.prototype.toString()

Returns a string representing the specified object in the specified radix (base). The inverse function is parseInt(s,r). This function is also called automatically when the object is treated as a string.

Number.prototype.toLocaleString()

Returns a string with a language sensitive representation of this number. Overrides the Object.prototype.toLocaleString() method.(Refer to 6.20 for related information on Intl.)

toString() can be used to convert the base of a number to an artrary radix.
var n = 123.456;

console.log(n.valueOf());

console.log(n.toExponential());
console.log(n.toExponential(4));

console.log(n.toFixed());
console.log(n.toFixed(4));

console.log(n.toPrecision());
console.log(n.toPrecision(4));

console.log(n.toString() + 999);
console.log(n.toString(16));

console.log((1234567).toLocaleString());
console.log((123.4).toLocaleString("zh-Hans-CN-u-nu-hanidec"));
console.log((2500).toLocaleString("en-GB", { style: "currency", currency: "GBP", minimumFractionDigits: 2 }));

123.456 1.23456e+2 1.2346e+2 123 123.4560 123.456 123.5 123.456999 7b.74bc6a7ef9dc 1,234,567 一二三.四 £2,500.00