in escodegen.js [2056:2074]
withIndent(function (indent) {
var i, iz;
for (i = 0, iz = expr.elements.length; i < iz; ++i) {
if (!expr.elements[i]) {
if (multiline) {
result.push(indent);
}
if (i + 1 === iz) {
result.push(',');
}
} else {
result.push(multiline ? indent : '');
result.push(that.generateExpression(expr.elements[i], Precedence.Assignment, E_TTT));
}
if (i + 1 < iz) {
result.push(',' + (multiline ? newline : space));
}
}
});