bigdecimal.js

The values passed must match one of Java BigDecimal's constructors, so the valid usages of this function is listed below:

Big(123n); // bigint, 123
Big(123n, 3); // bigint and scale, 0.123
Big(123n, 3, MC(2, RoundingMode.HALF_UP)); // bigint, scale and mc, 0.12
Big(123n, undefined, MC(2, RoundingMode.HALF_UP)); // bigint and mc, 1.2E+2
Big('1.13e12'); // string, 1.13E+12
Big('1.11e11', undefined, MC(2, RoundingMode.HALF_UP)); // string and mc, 1.1E+11
Big(10000); // number, 10000
Big(123, 5); // integer and scale, 0.00123
Big(1.1233, undefined, MC(2, RoundingMode.HALF_UP)); // number and scale, 1.1

Sample Usage:

const { Big } = require('bigdecimal.js');

// Constructor accepts any value such as string and BigDecimal itself:

const x = Big('1.1111111111111111111111');
const y = Big(x);

const z = x.add(y);
console.log(z.toString()); // 2.2222222222222222222222


const u = Big(1.1);
const v = Big(2n);

// You can also construct a BigDecimal from a number or a BigInt:

console.log(u.toString()); // 1.1
console.log(v.toString()); // 2

Sample Usage:

const { Big, MathContext, RoundingMode } = require('bigdecimal.js');

const x = Big('1');
const y = Big('3');

const res1 = x.divide(y, new MathContext(3));
console.log(res1.toString()); // 0.333

const res2 = x.divide(y, MathContext(3, RoundingMode.UP)); // You can also use without `new` operator
console.log(res2.toString()); // 0.334

try {
    x.divide(y);
    // throws since full precision is requested but it is not possible
} catch (e) {
    console.log(e); // RangeError: Non-terminating decimal expansion; no exact representable decimal result.
}