Compatibility

njs is created in compliance with ECMAScript 5.1 (strict mode) with some ECMAScript 6 and later extensions. The compliance is still evolving.

• Boolean values, numbers, strings, objects, arrays, functions, and regular expressions
• ES5.1 operators, ES7 exponentiation operators
• ES5.1 statements: var, if, else, switch, for, for in, while, do while, break, continue, return, try, catch, throw, finally
• ES6 Number and Math properties and methods
• String methods:
  • ES5.1: fromCharCode, concat, slice, substring, substr, charAt, indexOf, lastIndexOf, toLowerCase, toUpperCase, trim, search, match, split, replace
  • ES6: fromCodePoint, codePointAt, includes, startsWith, endsWith, repeat
  • ES8: padStart, padEnd
  • non-standard: bytesFrom (0.2.3) fromUTF8, toUTF8, fromBytes, toBytes
• Object methods:
  • ES5.1: create (support without properties list), keys, defineProperty, defineProperties, getOwnPropertyDescriptor, getPrototypeOf, hasOwnProperty, isPrototypeOf, preventExtensions, isExtensible, freeze, isFrozen, seal, isSealed
  • ES8: entries (0.2.7), values (0.2.7)
• Array methods:
  • ES5.1: isArray, slice, splice, push, pop, unshift, shift, reverse, sort, join, concat, indexOf, lastIndexOf, forEach, some, every, filter, map, reduce, reduceRight
  • ES6: of, fill, find, findIndex
  • ES7: includes
• ES5.1 Function methods: call, apply, bind
• ES5.1 RegExp methods: test, exec
• ES5.1 Date methods
• ES5.1 JSON object
• ES5.1 arguments object (0.2.5)
• ES6 rest parameters syntax (without destructuring support) (0.2.7)
• ES5.1 global functions: isFinite, isNaN, parseFloat, parseInt, decodeURI, decodeURIComponent, encodeURI, encodeURIComponent
• Error objects: Error, EvalError, InternalError, RangeError, ReferenceError, SyntaxError, TypeError, URIError
• setTimeout and clearTimeout functions (0.2.0)
• Node.js style File system methods: fs.readFileSync, fs.appendFileSync, fs.writeFileSync
• Node.js style Crypto methods (0.2.0): crypto.createHash, crypto.createHmac

• ES6 let and const declarations
• labels
• eval function
• new Function() constructor
• setInterval, setImmediate functions