CONTRIBUTING.md

Contributing

Documentation

Every new feature and API change should be accompanied by a README addition.

Enabling dev mode

Normally when you require terser or use the CLI, you get a compiled version. When developing terser, you want to use the files you're actually editing to make those tests pass. So, add to your .bashrc: TERSER_NO_BUNDLE=1.

Testing

All features and bugs should have tests that verify the fix. You can run all tests using npm test.

The most common type of test are tests that verify input and output of the Uglify transforms. These tests exist in test/compress. New tests can be added either to an existing file or in a new file issue-xxx.js.

Tests that cannot be expressed as a simple AST can be found in test/mocha.

Code style

• File encoding must be UTF-8.
• LF is always used as a line ending.
• Statements end with semicolons.
• Indentation uses 4 spaces, switch case 2 spaces.
• Identifiers use snake_case.
• Strings use double quotes (").
• Use a trailing comma for multiline array and object literals to minimize diffs.
• The Uglify code only uses ES5.
• Line length should be at most 80 cols, except when it is easier to read a longer line.
• If both sides of a comparison are of the same type, == and != are used.
• Multiline conditions place && and || first on the line.
• Code must pass the lint (npm run lint, or npm run lint-fix for auto-fix).

Example feature

OPT(AST_Debugger, function(self, compressor) {
    if (compressor.option("drop_debugger"))
        return make_node(AST_EmptyStatement, self);
    return self;
});

Example test case

drop_debugger: {
    options = {
        drop_debugger: true,
    }
    input: {
        debugger;
        if (foo) debugger;
    }
    expect: {
        if (foo);
    }
}