let keyword in the for loop

by

squint’s answer is no longer up-to-date. In ECMA 6 specification, the specified behaviour is that in 

for(let i;;){}

i gets a new binding for every iteration of the loop.

This means that every closure captures a different i instance. So the result of 012 is the correct result as of now. When you run this in Chrome v47+, you get the correct result. When you run it in IE11 and Edge, currently the incorrect result (333) seems to be produced.

More information regarding this bug/feature can be found in the links in this page;

Since when the let expression is used, every iteration creates a new lexical scope chained up to the previous scope. This has performance implications for using the let expression, which is reported here.

More Related Contents:

  1. Unable to access React instance (this) inside event handler [duplicate]
  2. Javascript object literal: what exactly is {a, b, c}?
  3. Is it possible to import modules from all files in a directory, using a wildcard?
  4. Why does babel rewrite imported function call to (0, fn)(…)?
  5. Call async/await functions in parallel
  6. ES6 Modules: Undefined onclick function after import
  7. How to import jquery using ES6 syntax?
  8. ES6 Promise.all() error handle – Is .settle() needed? [duplicate]
  9. What are the actual uses of ES6 WeakMap?
  10. Why are ES6 classes not hoisted?
  11. Filtering an array with a function that returns a promise
  12. Can I set the filename of a PDF object displayed in Chrome?
  13. When should I use brackets with imports
  14. How do I make a “public static field” in an ES6 class?
  15. comparing ECMA6 sets for equality
  16. es6 import for side effects meaning
  17. Get list of duplicate objects in an array of objects
  18. What is the difference between importing a function expression or a function declaration from a ES6 module?
  19. Error: How to serialize data from getStaticProps : Next.js
  20. Update one of the objects in array, in an immutable way
  21. Access to Script at ‘ from origin ‘null’ has been blocked by CORS policy
  22. How to namespace es6 classes (for React components)
  23. set withCredentials to the new ES6 built-in HTTP request API : Fetch
  24. Why will ES6 WeakMap’s not be enumerable?
  25. How does JavaScript import find the module without an extension?
  26. What is ‘global symbol registry’?
  27. Exporting functions with reactjs and babel
  28. object destructuring: how to use intermediate nested property
  29. Compare two Arrays with Objects and create new array with unmatched objects
  30. When is the body of a Promise constructor callback executed?

Leave a Comment