src/lang-javascript.js

'use strict';
const esprima = require('esprima');

module.exports = {
	name: 'lang-javascript',
	esprima: esprima,
	parser: function parser(code, options) {
		options = options || {};
		let opts = {loc: true, range: true};
		if ( options.inFunctionBody ) {
			opts.tolerant = true;
			opts.allowReturnOutsideFunction = true;
		}

		let ast = esprima.parse(code, opts);
		let errors = [];
		if ( ast.errors ) {
			errors = ast.errors.filter((x) => {
				if ( options.inFunctionBody && x.message === 'Illegal return statement' ) return false;
			});
		}
		delete ast.errors;
		if ( errors.length > 0 ) throw errors[0];
		return ast;
	}
};