JavaScript CodeModel

JavaScript CodeModel project (JSCM for short) provides a Java API for programmatic creation and manipulation of JavaScript source code.

JSCM models grammatical structure of JavaScript (accoring to the ECMAScript specification) in Java classes. This allows building JavaScript code from Java programmatically.

Once object model of the JavaScript program is built, it can be formatted and printed out into a writer. The result is well-formatted (with indentation, line breaks etc.) and is almost guaranteed to be in correct JavaScript syntax.

Using JavaScript CodeModel

Usage is rather straightforward. Here's a small example:

// Instantiate the code model
JSCodeModel codeModel = new CodeModelImpl();
// Create the program
JSProgram program = codeModel.program();
// Add a function declaration
JSFunctionDeclaration factorial = program
	.functionDeclaration("factorial");
// Add a function parameter
JSVariable x = factorial.parameter("x");
// Create an integer literal
JSDecimalIntegerLiteral one = codeModel.integer(1);
// Add a return statement to the function body
factorial.getBody()._return(
	x.le(one).cond(
		one,
		x.mul(factorial.getFunctionExpression().i()
			.args(x.minus(one)))));

// Write the program code to the System.out
new CodeWriter(System.out).program(program);

This produces the following JavaScript code:

function factorial(x) {
  return x <= 1 ? 1 : x * factorial(x - 1);
}

Getting JavaScript CodeModel

For a single JAR file, check releases.

If you're using Apache Maven (or compatible build tools), please use the following dependency:

<dependency>
	<groupId>org.hisrc.jscm</groupId>
	<artifactId>js-codemodel</artifactId>
	<version>...</version>
</dependency>

Limitations

JSCM models JavaScript grammar with high precision. However there are certain things we've not implemented at the moment.

• Comments are not supported at the moment.
• Regular expressions are not supported at the moment.
• Identifier names are not checked for correctness.
• It is possible to create a construct like for (var x in y in z) { ... }