JavaScript: Print an integer with commas as thousands separators

JavaScript validation with regular expression: Exercise-21 with Solution

Thousands Separator

Write a JavaScript function to print an integer with thousands separated by commas.

Visual Presentation:

Sample Solution:

JavaScript Code:

function thousands_separators(num)
  {
    var num_parts = num.toString().split(".");
    num_parts[0] = num_parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    return num_parts.join(".");
  }

console.log(thousands_separators(1000));
console.log(thousands_separators(10000.23));
console.log(thousands_separators(100000));

Output:

1,000
10,000.23
100,000

Flowchart:

Live Demo:

See the Pen javascript-regexp-exercise-21 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that formats a number with commas as thousands separators using a regular expression.
• Write a JavaScript function that manually inserts commas into a number by converting it to a string and processing its digits.
• Write a JavaScript function that handles numbers with decimal parts and ensures only the integer part is comma-separated.
• Write a JavaScript function that validates numeric input and returns a formatted string with thousands separators for both positive and negative numbers.

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