preserveBlankLines does not work.

var ast = esprima.parse(code, {
    loc: true,
    range: true,
    comment: true,
    tokens: true
});

gen.attachComments(ast, ast.comments, ast.tokens);

var output = gen.generate(ast, {
    format: {
        compact: false,
        preserveBlankLines: true
    },
    comment: true,
    sourceMap: 'script.js',
    sourceMapWithCode: true
});

Disappointingly, blank line is removed from code.

[dtothefp]

any additional info on this, would be nice to preserve newlines and seems like a simple feature that doesn’t work?

[ghost]

The way I preserved blank lines was like this:

const whitespaceMarker = "// {Guid goes here}"
let programLines = program.split('\n');
let replacedProgramLines = programLines.map(line => {
    // If the line is blank or nothing but whitespace, return the whitespace marker as a comment.
    if (line.length === 0 || /^\s+$/.test(line)) {
        return whitespaceMarker;
    }

    return line;
});

let replacedProgram = replacedProgramLines.join('\n');   
let syntax = esprima.parse(replacedProgram, {
    raw: true,
    tokens: true,
    range: true,
    comment: true
}); 
escodegen.attachComments(syntax, syntax.comments, syntax.tokens);

// ...

let output = escodegen.generate(syntax, {
    comment: true
});
let replacedOutput = output.split(whitespaceMarker).join('');

This mostly works. I noticed today that sometimes a newline is omitted.