JavaScript Pretty Print: Format Minified Code

Ever opened a JavaScript file that was squeezed onto one long line? Minified code saves bytes, but it is painful to read. JavaScript Pretty Print takes that wall of code and breaks it into indented lines you can actually follow.

This tool is for developers, students, and anyone reviewing a script. You paste raw JavaScript, and the formatted version appears as you type. Everything runs in your browser, so your code never leaves your computer.

Table of Contents

• What the Tool Does
• How to Use It, Step by Step
• How the Formatter Works
• Worked Example
• How to Read the Results
• What the Formatter Protects
• Limitations and Assumptions
• FAQs About the JavaScript Pretty Print

What the Tool Does

The tool adds line breaks and indentation to JavaScript source. It reads your input and reshapes the layout around a few symbols.

• Raw JS Input: the box where you paste the code you want to format.
• Formatted JS Output: a read only box that shows the indented result.
• Original Length: the size of your input in bytes, shown with a "B" label.
• Formatted Size: the size of the output in bytes, also labeled "B".
• Code Lines: how many lines the formatted output has.
• Clear empties the input, and Copy JS copies the formatted output.

It only reshapes the layout. The output keeps every character of your input in the same order.

How to Use It, Step by Step

1. Paste your code into the Raw JS Input box. A sample loads by default.
2. Watch the Formatted JS Output update on every keystroke. There is no button to press.
3. Check the three cards on top for size and line counts.
4. Press Copy JS to send the formatted code to your clipboard.
5. Press Clear to empty the input and start over.

How the Formatter Works

The tool scans your code one character at a time. It reacts to a few symbols and copies everything else as is.

• An open brace adds a space, a line break, and one more level of indent.
• A close brace steps back one level and puts the brace on its own line.
• After a close brace, the next statement starts on a fresh line.
• A semicolon adds a line break and keeps the current indent.
• Each indent level is two spaces, so nested blocks step inward.

At the end, blank lines are collapsed and extra edge spaces are trimmed.

Worked Example

Suppose Priya pastes a short snippet with two statements crammed together. The input is 38 characters long.

The semicolon after the 1 ends the first line. The open brace starts an indented block, and the close brace drops back out. The output reads like this, across four lines:

• const a=1;
• function sum(x) {
•   return x+1;
• }

The tool added a space before the brace, two line breaks, and two spaces of indent. That is why 38 bytes grew to 44.

How to Read the Results

Original Length measures your input in true UTF-8 bytes. Plain English text counts as one byte per character, while emoji and accented letters count as more.

Formatted Size measures the output in bytes. It is usually larger, since spacing is added. Minified input almost always grows here.

Code Lines is the number of lines in the output. Each semicolon and brace tends to add a line, so this rises with block count.

What the Formatter Protects

This is a light formatter, not a full parser. Even so, it guards the parts of your code that must stay untouched.

Text inside single quotes, double quotes, and backtick templates is copied word for word. Line comments and block comments are copied the same way. A semicolon or brace inside these parts will not trigger a break.

Regular expression literals are also kept whole. A slash that starts a regex is read as a pattern, not as division. So quotes inside it do not confuse the scanner. A string that ends with an escaped backslash still closes correctly.

Semicolons inside parentheses stay on the same line. That keeps a for loop header, which holds two inner semicolons, on a single tidy line.

Limitations and Assumptions

• The tool only adds spacing. It never fixes syntax errors or missing semicolons.
• It does not align operators, wrap long lines, or group import statements.
• An array of objects can still format a little roughly, since the scanner has no object context.
• Regex detection is a smart guess, so a rare edge case may read a slash as division.
• Input above 100,000 characters is blocked, and a notice asks you to shorten it.
• There is no minify mode here. To shrink code, use the JavaScript minifier instead.

If you need fuller formatting rules, try the JavaScript beautifier. For other languages, the JSON formatter and the CSS beautifier follow the same browser based idea. You can find more utilities in the developer tools hub.

FAQs About the Js Pretty Print

This calculator gives general estimates only and is not professional advice. Reviewed for general accuracy by Prof. Dr. Khalil Mudassar, PhD.