JavaScript: Print an integer with commas as thousands separators

JavaScript Math: Exercise-39 with Solution

Format Integer with Thousands Separator

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

Test Data:
console.log(thousands_separators(1000));
"1,000"
console.log(thousands_separators(10000.23));
"10,000.23"
console.log(thousands_separators(100000));
"100,000"

Sample Solution:

JavaScript Code:

// Define a function named thousands_separators that adds thousands separators to a number.
function thousands_separators(num)
{
    // Convert the number to a string and split it into an array containing the integer part and the decimal part.
    var num_parts = num.toString().split(".");
    // Add thousands separators to the integer part using a regular expression.
    num_parts[0] = num_parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
    // Join the integer and decimal parts back together with a period and return the result.
    return num_parts.join(".");
}

// Output the result of adding thousands separators to 1000 to the console.
console.log(thousands_separators(1000));
// Output the result of adding thousands separators to 10000.23 to the console.
console.log(thousands_separators(10000.23));
// Output the result of adding thousands separators to 100000 to the console.
console.log(thousands_separators(100000));

Output:

1,000
10,000.23
100,000

Visual Presentation:

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-39 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that inserts commas as thousands separators into an integer using regular expressions.
• Write a JavaScript function that formats both integers and floating-point numbers with proper thousands grouping.
• Write a JavaScript function that manually iterates through a number's digits to insert commas at appropriate intervals.
• Write a JavaScript function that processes large numbers and ensures the decimal portion remains unaltered during formatting.

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