Why does the `then()` handler of a promise execute immediately?

by 
promise.then(alert('after delay'));

Here you:

  1. Call alert()
  2. Pass its return value to then()

So the promise doesn’t resolve immediately. You just alert before it resolves.

You have to pass a function to then.

promise.then(alert.bind(window, 'after delay'));

More Related Contents:

  1. How to wait until promise finishes before continuing the loop
  2. How do I access previous promise results in a .then() chain?
  3. Chained promises not passing on rejection
  4. How do I promisify native XHR?
  5. How to synchronize a sequence of promises?
  6. Promise.all: Order of resolved values
  7. How can I fetch an array of URLs with Promise.all?
  8. Does never resolved promise cause memory leak?
  9. What does $.when.apply($, someArray) do?
  10. Why is ‘this’ undefined inside class method when using promises? [duplicate]
  11. NodeJS Timeout a Promise if failed to complete in time
  12. for await of VS Promise.all
  13. Can promises have multiple arguments to onFulfilled?
  14. resolving an array of promises from within a parent promise
  15. Are JavaScript Promise asynchronous?
  16. Promise : then vs then + catch [duplicate]
  17. Is there a way to return early in deferred promise?
  18. When to use promise.all()?
  19. Using setInterval() with a .map method in array and returning as a promise
  20. Why are javascript promises asynchronous when calling only synchronous functions?
  21. Creating a (ES6) promise without starting to resolve it
  22. Are there differences between .then(functionReference) and .then(function(value){return functionReference(value)})?
  23. Is there a way to know if a link/script is still pending or has it failed
  24. Return value from a Promise constructor
  25. Why does .then() chained to Promise.resolve() allow const declaration to be reassigned?
  26. Is it possible to use axios.all with a then() for each promise?
  27. Memoization of promise-based function
  28. Return value of Promise’s resolve/reject functions
  29. Why is try {} .. catch() not working with async/await function?
  30. Weird behavior with Promise throwing “Unhandled promise rejection” error

Leave a Comment