how to know which javascript version in my NODEJS?
Use process.versions. From that page in the documentation: console.log(process.versions); outputs { node: ‘0.4.12’, v8: ‘3.1.8.26’, ares: ‘1.7.4’, ev: ‘4.4’, openssl: ‘1.0.0e-fips’ } EDIT: V8 uses the ECMAScript as specified in ECMA-262, 5th edition. Reference: http://code.google.com/p/v8/