util.formatWithOptions() Method in Node.js

In Node.js, the util.formatWithOptions() method, available in the built-in util module, offers enhanced string formatting capabilities. It provides more control over how data is formatted compared to util.format(), making it easier to handle complex output requirements.

What is util.formatWithOptions()?

The util.formatWithOptions() method formats a string using placeholders and values, with an added twist — it accepts an options object that allows customization of the output. This is particularly useful for enabling colors, controlling depth in objects, and showing hidden properties.

Basic Syntax

Here is the basic syntax for using this method:

util.formatWithOptions(inspectOptions, formatString, ...args)

Example

Let’s look at a simple example:

const util = require('util');

const result = util.formatWithOptions(
    { colors: true },
    'Hello %s, you have %d new messages.',
    'Bob',
    5
);

console.log(result);

This will format the string and apply color coding if the terminal supports it.

Common Options

• colors: Adds color to the output for better readability in the terminal.
• depth: Specifies how deep nested objects should be printed.
• showHidden: If true, includes non-enumerable properties in the output.

Advanced Example

Here's a more advanced use case with nested objects and additional options:

const util = require('util');

const user = {
    name: 'Alice',
    details: {
        age: 30,
        location: {
            city: 'New York',
            zip: 10001
        }
    }
};

const formatted = util.formatWithOptions(
    { colors: true, depth: 3 },
    'User: %O',
    user
);

console.log(formatted);

When to Use

• For debugging deeply nested objects with better formatting
• When you want to customize how objects appear in logs
• To enable color in terminal outputs for better visibility

Conclusion

The util.formatWithOptions() method in Node.js is a flexible and powerful tool for customizing string outputs. Whether you're debugging, inspecting data, or enhancing your logs, this method provides options to make your output more informative and easier to understand.