Javascript number formatting 12345 → 12.345

javascript_number_dot_formatting.js

function dots(number, separator = '.') {
  return number.toString().replace(/\B(?=(\d{3})+(?!\d))/g, separator);
}

// Positive tests

console.assert(dots(0) === "0");
console.assert(dots(1) === "1");
console.assert(dots(12) === "12");
console.assert(dots(123) === "123");
console.assert(dots(1234) === "1.234");
console.assert(dots(12345) === "12.345");
console.assert(dots(123456) === "123.456");
console.assert(dots(1234567) === "1.234.567");
console.assert(dots(12345678) === "12.345.678");
console.assert(dots(123456789) === "123.456.789");
console.assert(dots(1234567891) === "1.234.567.891");

console.assert(dots(10) === "10");
console.assert(dots(100) === "100");
console.assert(dots(1000) === "1.000");
console.assert(dots(10000) === "10.000");
console.assert(dots(100000) === "100.000");
console.assert(dots(1000000) === "1.000.000");
console.assert(dots(10000000) === "10.000.000");
console.assert(dots(100000000) === "100.000.000");
console.assert(dots(1000000000) === "1.000.000.000");
console.assert(dots(1001050003) === "1.001.050.003");

// Negative tests

console.assert(dots(-0) === "0");
console.assert(dots(-1) === "-1");
console.assert(dots(-12) === "-12");
console.assert(dots(-123) === "-123");
console.assert(dots(-1234) === "-1.234");
console.assert(dots(-12345) === "-12.345");
console.assert(dots(-123456) === "-123.456");
console.assert(dots(-1234567) === "-1.234.567");
console.assert(dots(-12345678) === "-12.345.678");
console.assert(dots(-123456789) === "-123.456.789");
console.assert(dots(-1234567891) === "-1.234.567.891");

console.assert(dots(-10) === "-10");
console.assert(dots(-100) === "-100");
console.assert(dots(-1000) === "-1.000");
console.assert(dots(-10000) === "-10.000");
console.assert(dots(-100000) === "-100.000");
console.assert(dots(-1000000) === "-1.000.000");
console.assert(dots(-10000000) === "-10.000.000");
console.assert(dots(-100000000) === "-100.000.000");
console.assert(dots(-1000000000) === "-1.000.000.000");

// Using custom separator

console.assert(dots(0, ',') === "0");
console.assert(dots(1, ',') === "1");
console.assert(dots(12, ',') === "12");
console.assert(dots(123, ',') === "123");
console.assert(dots(1234, ',') === "1,234");
console.assert(dots(12345, ',') === "12,345");
console.assert(dots(-123456, ',') === "-123,456");
console.assert(dots(-1234567, ',') === "-1,234,567");
console.assert(dots(-12345678, '\'') === "-12'345'678");
console.assert(dots(-123456789, '\'') === "-123'456'789");
console.assert(dots(-1234567891, '\'') === "-1'234'567'891");