Constants in JavaScript

Go supports constants of character, string, boolean, and numeric values.

const declares a constant value:

const s = "constant";
console.log(s);

A const statement can appear anywhere a var statement can.

const n = 500000000;

Constant expressions perform arithmetic with arbitrary precision.

const d = 3e20 / n;
console.log(d);

A numeric constant has no type until it’s given one, such as by an explicit conversion.

console.log(BigInt(d));

A number can be given a type by using it in a context that requires one, such as a variable assignment or function call. For example, here Math.sin expects a number.

console.log(Math.sin(n));

To run the program, save the code in a file (e.g., constants.js) and use node to execute it:

$ node constants.js
constant
6e+11
600000000000n
-0.28470407323754404

Now that we can run and build basic JavaScript programs, let’s learn more about the language.