CoffeeScript to JavaScript Converter Online

This CoffeeScript to JavaScript converter compiles CoffeeScript source into standard ES6 JavaScript directly in your browser. Paste, write, or upload CoffeeScript code, choose compile and formatting options, and get clean JavaScript you can copy or download without any server upload.

Core capabilities

  • Convert CoffeeScript to JavaScript instantly in the browser
  • Choose bare mode to remove the top level safety wrapper when you need global variables
  • Generate inline source maps or supply a filename for external maps and better error reporting
  • Built in JS beautifier for pretty output
  • Run locally in the browser so your CoffeeScript code never leaves your machine

How to use this CoffeeScript to JS converter

  1. Write, paste or upload your CoffeeScript into the input editor
  2. Pick options for bare mode, source maps, and formatting to match your workflow
  3. Click Convert to transpile CoffeeScript to JavaScript
  4. Inspect the generated JS in the output pane, use beautify for readable code, then copy or download the file

Why convert CoffeeScript to JavaScript

Converting CoffeeScript to JavaScript ensures compatibility with modern browsers and tool chains, reduces friction when integrating into existing builds, and creates a clear path to ES6 or TypeScript migrations while preserving original logic and intent.

Key differences: CoffeeScript source vs compiled JavaScript

  • CoffeeScript is concise, using whitespace and minimal syntax
  • JavaScript is explicit and supported natively by all browsers
  • Compilation expands CoffeeScript sugar into plain JavaScript
  • Compiled JS output can target ES5, ES6, or later versions
  • CoffeeScript favors readability, JavaScript favors flexibility
  • Debugging is easier in compiled JavaScript with source maps

Example 1: Simple function

CoffeeScript Code

Copy
square = (x) -> x * x
console.log square 5

Converted JS Code

Copy
(function() {
    var square;

    square = function(x) {
        return x * x;
    };

    console.log(square(5));

}).call(this);
console.log(square(5));

Example 2: Class and mapping

CoffeeScript Code

Copy
class Person
  constructor: (@name) ->
  greet: -> "Hello #{@name}"

people = ["Alice", "Bob"].map (n) -> new Person n

Converted JS Code

Copy
(function() {
    var Person, people;

    Person = class Person {
        constructor(name) {
            this.name = name;
        }

        greet() {
            return `Hello ${this.name}`;
        }

    };

    people = ["Alice", "Bob"].map(function(n) {
        return new Person(n);
    });

}).call(this);

Customization options

The table lists every option available in the editor to customize the output.

Option Default Description
BARE False Compile without a top level function safety wrapper so variables become global
Header False Include the header comment in the output
Inline Map False Embed a source map as a data URI inside the compiled JavaScript
Filename empty Optional filename used in source maps and in error reporting
Indent Size 4 Number of spaces per indent level for beautified output
Indent Char Space Character used for indentation in beautified output
Use Tabs False Indent using tabs instead of spaces
EOL LF End of line character for the output file options include LF, CRLF, and CR
Ending Newline False Add a newline at the end of the output file
Keep Newlines True Preserve existing line breaks from the source
Indent Level 0 Initial indentation depth applied to the entire output
Max Newlines 3 Maximum consecutive line breaks to preserve
Space in parentheses False Add a space inside parentheses when true
Empty parentheses space False Add a space inside empty parentheses when true
Anon function space False Insert a space before parentheses in anonymous functions
Named function space False Insert a space before parentheses in named functions
Brace style collapse Style used for block braces options include collapse expand end expand and none
Break chains False Place each chained method call on a new line
No chain indent False Do not indent chained methods
Keep arrays False Preserve original array formatting
Unescape False Unescape printable xNN strings in the output
Wrap length 0 Wrap lines that exceed this length zero disables wrapping
Comma first False Place commas at the start of lines when true
Operator position before newline Position of operators when wrapping lines options include before newline after newline and preserve original
Indent empty lines False Keep indentation on otherwise empty lines

Best Practices

  • Store CoffeeScript in source control, commit JS only when needed
  • Enable source maps to trace errors back to CoffeeScript
  • Beautify for development, minify for production builds
  • Lint compiled JS before merging into larger projects
  • Keep CoffeeScript and compiled JS in separate folders
  • Automate compilation with build or CI pipelines

Conclusion

Use this CoffeeScript to ES6 JavaScript converter to transpile your CS to JS quickly and safely. Configure bare mode and source maps for accurate error reporting, choose customization options, and download production ready JavaScript in seconds.