What's new in ES{5,6}

ES2015.md

• Block scopes with let and const
  • let in for loop rebinds variable on each iteration
• lexical this (instead of dynamic one) with arrow functions
• method definitions ?
• shorthand object properties
  • var = {foo, bar}
• computed property names
  • { [name()]: value }
• getter & setter methods
• Symbols
  • custom for of: Symbol.iterator
• classes
  • can contain only method definitions (no data fields)
  • constructor / static methods / prototype methods / symbol methods
  • useless subtlety: new.target
• string interpolation with ${}
  • String.raw to escape backslashes
• new collections
  • Map (arbitrary datatypes as keys -- not only strings as in objects)
    • set / get / has / delete / clear / forEach / keys / values / entries
    • using objects as maps are still ok if you know your key-value pairs when you write your code
    • iterating over the entries is tricky if you use objects
    • maps preserve order of insertions when iterating
  • Set
    • add / has / delete / clear
  • WeakMap / WeakSet
• generators
  • beware of return and for .. of
  • delegating generators with yield *
  • async programming
    • see: https://davidwalsh.name/async-generators
    • see: https://davidwalsh.name/concurrent-generators

Links

• https://scotch.io/tutorials/better-node-with-es6-pt-i
• https://scotch.io/tutorials/better-javascript-with-es6-pt-ii-a-deep-dive-into-classes
• https://scotch.io/tutorials/better-javascript-with-es6-pt-iii-cool-collections-slicker-strings
• https://davidwalsh.name/es6-generators
• http://exploringjs.com/es6/ch_overviews.html
• http://frontender.info/asynchronous-javascript/